TURRET CLOCKS.

form an aliquot part of 12, we must make an allow-
ance for it. Suppose, for instance, that the substiler
line should not be on the line of X., but between IX.
SIR,-Several correspondents in the last number of
and X., we must find how much to allow for it before the MECHANIC ask for more information about the
commencing our reckoning. For the sake of example, clock I described in your pages a short time ago; I
suppose the longitude should be 2h. 20min. This, will, with your permission, afford them it. Enclosed
converted into degrees, will be 35°, and using the is a drawing, showing how the quarter train is dis-
same formula-namely, R; sin. 14:: tan. 5: tan. dist. charged and stopped. A is the pin wheel. Three
-we shall have 1° 13. Having measured this distance times in the hour a pin presses down the lifting piece
from the substiler line, we must compute the hour-B, which has two bits of steel rivetted in it. The
arcs by taking it in, and instead of taking tan. 15°, locking arm C has also a bit of steel, which comes
tan. 30°, &c., we must take tan. 20°, tan. 35°, &c., against the stop on the lifting piece, when it is allowed
adding 5° to each; but in the morning hours, by the to fall by the wedge of hard steel rivetted in it drop.
same process, we find we must allow 2° 28' from the ping into the notch in the cam wheel D, and the detent
substiler line to the hour of IX., and instead of tan. 15o, Finto the notch in the locking plate E. When the
tan. 30°, &c., we must add 10°, and compute by tan end of the lifting piece is pressed by one of the pins,
25°, tan. 40°, &c.; and by working them out in this the heavy end rises, and lets one of its stops slip past
way we shall obtain all the hour-ares. In conclu- the stop on the locking arm C, which moves forward
sion, we must remember in all these kinds of dials in the direction of the arrow, and comes against the
to place the gnomon parallel with the axis of the warning stop two or three minutes before the quarter
world, or point to the poles, and to apply the equation is to be struck. When the end is free of the pin, the
of time when we set our clockwand watches by them, heavy part falls back into its former place, the cam
and then, like the great sun of the universe, we may wheel revolves and raises the stops on the lifting
always depend upon an unerring guide to direct us to piece out of the way of the locking arm, and the num-
our several duties.
T. S. H.

P.S. Your highly-instructive correspondent "F.R.A.S.," whose papers it is a pleasure to peruse, recommends "Heather on Mathematical Instruments and Dialling Scales," but I venture to say that although its contents are most valuable, and its directions on dialling quite sufficient for those to whom the art is like A BC, yet it is not full enough for others, nor does it give any directions whatever for the construction of declining and reclining dials. The hour

arcs may also be found by that useful rule, the sector, but with much more trouble and far less accuracy than by the method prescribed, which is nothing more than addition and subtraction. In last letter, page 15, in the diagram, for "60" read "68°;" and for the "angle A C B 309 + 90◄ " read "angle A C B 27° + 90°."

EXPLANATORY.

SIR-I cannot see anything in my letters entitling "FRA.S." to suppose I had him in my thoughts when I referred to what the German poet has said about "strong men." All the same, I would submit to him my doubts whether it befits a real lover of science, as he undoubtedly is, to "eschew discussion ab initio on every moot point whatever; " nor can I think that the abandonment of "a winning cause" (in itself hardly a commendable thing) would justify the course of dropping an argument when one finds one has made a

mistake.

ber of strokes is determined by the distance of the notches in the locking plate, which, in this case, is also the pin plate, and works two levers. The lifting piece B must fall quite dead, or it may fail to stop the train, and therefore the detent F must not touch the bottom of the notch. The hour-discharging mechanism is the same, only then the locking plate I have brought no charge of either sort, however, does not work the hammer lever, and the lifting piece against F.R.A.S.," for whose scientific attainments end is not pressed down, but raised by the pin in the and surprising general accuracy (when one considers the wide range of objects he treats of) I have the high-going part, I said nothing about the dial work, or the est possible respect. If I were disposed to do so, I way the pointers are driven, because it is not done in should be far more inclined to dwell on his spectrum the usual way. analysis illustration than on his theory respecting object glasses. The latter is a matter of opinion, the former a question of fact; and any one who is desirous, as I confess I am, of seeing the truth laid as clearly as possible before people, might fairly object to a statement which is opposed, I submit, to the very principles on which spectroscopic analysis depends.

But in praising (as was just) our contributor T. A." I was not "making a cap; "so that I need dwell no farther on a discussion which I also have desired to drop.*

RICHARD A. PROCTOR.

There was an old thirty hour clock, which had been going for nearly two hundred years, and was about showing the hours. About three years ago I put worn out, already in the tower; it had only one hand, machinery to it for striking the quarters. Change published in the ENGLISH MECHANIC. I also put wheels were used, and I sent a description, which was another hand to the clock, showing the minutes. The hand was next the dial, fastened on a tube. I should method was simple, but objectionable, as the minute prefer to use dial wheels in the usual way; they would be much more costly than change wheels, When I removed the old clock, I found the wheels none the worse for their nearly three years' work. The quarters had been striking at their regular intervals, and I had been well repaid for my labours by hearing their musical sound.

on four bells, as at Westminster. It can be done very well with six bells, if they are in the key of E flat. I should be happy to describe the machinery, together with a novel method of fixing the hammers to the bells, if it would be of interest to your readers.

THE ILLUMINATED PORTION OF THE
MOON'S DISC.

SIR,-I think Mr. Beardsley is right in not accepting the explanations alrendly given as exhaustive; for if, when the moon is only two days old, an imaginary line be drawn from its centre, and made to pass through its surface in the centre of the edge of the illuminated are and prolonged, fa would not cut through the sum at all, but would be almost at right angles with that luminary; but a line drawn from the centre of the moon through that part of the surface which is in the centre of the illuminated half (for we all know that one-half of the moon is always to the sun was prolonged, it would cut through the centre of the sun.

Now, Sir, when the moon is about the end of the first or third quarter, one-half of the illuminated portion is turned towards the earth, the other half of the illuminated portion is turned away; therefore, in this case, the centre of the whole illuminated moon, and the centre of the illuminated edge as seen from the earth, coincide; so that in this part of its orbit the illuminated portion of the moon's disc is fairly directed to the sun, allowance being made for optical effects. W. F. SWALLOW.

BREAD-MAKING,

SIR, I cannot pass over "T. Estee's" letter with-
out a few words of comment upon it, as I certainly
think your correspondent has never tasted good
unfermented bread. We have used it for 21 years,
and scarcely ever failed in having excellent, sweet,
moist bread, As to its being injurious to the system,
I think it must be far otherwise, as I am myself an
invalid of many years' standing, and attribute my
present state of health entirely to the use of this
bread, As regards the recipe for baking powder
given by T. E," I think the quantity of rice so
large, that any one would fail to make good cakes or
pastry with it. Our proportions for baking powder
soda, 4 do.; ground rice, 1 do.
are as follows-viz., tartaric acid, 3oz.; bicarbonate of
mode of operation of making our bread in the space
As I cannot give the
of a letter, I must refer "T. E." to the Famay Friend
of 1850, vol. 2, page 176, where he will find the full
particulars.

THE AUTHOR OF THE ARTICLE ON UNFERMENTED
BREAD IN VOL. 2 OF "FAMILY FRIEND," 13T
SERIES.

'SIR,-"T. Estee" makes a vital mistake in confounding fermented with unfermented bread. The with a little water, while no amount of kneadlatter may be kneaded into a kind of raw paste ing will effect this change in the former, which, for persons, including the writer, cannot eat unfermented this reason, sits more lightly on the stomach. Many bread. Yeast acts chemically on flour, "powders "act any bookseller for theory, aud when you have spoiled mechanically. Buy a shilling treatise on baking of a few bakings and brewings you will find out how good sweet bread is made. If you value this commodity your trouble will not be lost. Don't try to make good bread out of bad flour. Don't let rice come in contact with yeast. NEW SUBSCRIBER.

CARBURETTING GAS.

"Ado

CRIMINAL LITERATURE. SIR, A clergyman, on the 31st ultimo, wrote under the above heading thus to the Times:"Sir,-A short time ago you recorded the conviction of A correspondent asks why I use cast iron wheels several vendors of immoral prints, not on the prosecution in preference to brass ones. Simply because iron SIR,-" Adolescens "asks, at p. 645, Vol. X., if he can of the Government, but of a society whose successful wheels cost only about a quarter of the price of brass fit gas burners to his 4in. condenser lanterns? and as I operations have made them insolvent. To-day you ones. No doubt the train is a coarse one, but with have done this for some years past, I am happy to record the words of Mobbe, the murderer:-I had weight enough on the barrel it will do its work well. tell him how I fitted them, as " V. W." page 659, proseen a picture of the man Baker murdering the girl in For the going part, 150lb. is hung on a 6in. diam. poses a method which I think would prove a very the hop-gardens.' Week after week the illustrated barrel; that is a great deal, but with a gravity escape- dangerous one, and 1 should like to know if he has records of crime are circulated over the length and ment it does not interfere with the time-keeping pro- actually used the arrangement he describes. breadth of the land. In my country parish the Illus-perty of the clock. I believe, from what I have seen lescens" will have to select very fine hole argand trated Police News has a large circulation. Its pictures of the performance of the clock-and I kept it going burners (32 will be required for such powerful lanterns represent crime in varied phases; its letter-press is in my workshop during the time the hour and quarter as he has), and they must be fitted with a conical ring explanatory; but its most damaging part is to be pasts were being done-that it will not vary more than round the outside of the burner, to cause a current of found in its advertisements. And yet as the law a minute in a month from mean time, when the pen-air to impinge upon the outside of the flame, and thus stands I much question if it can touch this publica-dulum, of varnished steel, is regulated. It takes about compress the flame to a smaller diameter. I have tion. Has no M.P, time to consider first and give half a minute to wind the going part up, and by lift- found with such burners that a common straight notice next of a motion upon this subject? Surely ing up a ratchet lever, geared to the third spindle, chimney gives the best light, but he must fit fine wire crime in England should have its share of considera- from below, a maintaining power is kept up. The gauze under the centre of the burners to obtain a pertion with crime in Ireland, and it strikes me that it is weight on the barrel of the hour part is 350lb., and fectly steady flame. Ordinary coal-gas will not give somewhat important to protect innocence as we lifts a hammer high enough to bring out the sound a sufficiently powerful or white light for lanterns, and spread education; but it unhappily appears that well from the tenor bell, weighing, I should say, 16 or must be carburetted, as described by "V. W.; " but I while we are squabbling as to whether religion may 17 cwt. The quarter bells in proportion. I obtained advise Adolescens" not to attempt to make a vessel be taught in our schools, we are permitting vice to be the change wheels of J. Buck, Newgate-street, but inside the lanterns, as, unless he is an experienced taught everywhere." Mr. Lloyd, 135, Steelhouse-lane, Birmingham, has hand, he will be very likely to have a dangerous explosent me his supplementary wheel list, and it appears sisu, as the heat of the lanterns in use would soon he can supply many other numbers of teeth besides cause the naphtha in the tin vessel to volatilise too those I mentioned, amongst others, the 130 tooth wheel rapidly and burst the vessel, or make a smoky flame I wanted, from excess of hydrogen vapour. A simpler and cheaper plan is to use a common glass round pickle bottle, which can stand on the floor or table, on one side of the lanterns, out of the way, and the whole affair will not cost 64., and yet answers the purpose admirably. Two pieces of compo. pipe, each 6in. long, must be fitted through a good bung in the mouth of the bottle, the inner end of one being flush with the bottom of the bung, and then curved to an elbow. The other must be thrust through the bung about half SIR,-I send you a few of the tests that have been way down the inside of the bottle, and the outer end put upon a telescope in my possession. It is 3in. also curved to an elbow. This will be for the inlet for aperture, 4ft. focus, 3 eye-pieces of 35, 60, and 96 Allow me, Sir, in conclusion, to say I like the new the gas. Now tie a sponge or large-sized argand cotton diameters. With the lowest power I can discern shape the ENGLISH MECHANIC has taken, and that I wick to the inner end of the pipe, on which a plug of Jupiter's satellites before sunset, and with the high-hope it will continue to be successful! I have sub-wood or a cork with a hole through it is fitted tightly, est power I have observed the transit of the satellites. scribed from the first, and have always endeavoured It shows distinctly 4 stars in the trapezium of Orion, to make it known to my mechanical friends. it splits Castor easily, shows the companion of Sirius, also Rigel; Cor Caroli it shows beautifully with the lowest power; Mizar also. I have seen the trapezium through a 3in. and 4in., and see 5 stars in one, and 6 in the other. The 3in. shows the belts of Jupiter more distinctly than a 7in. silvered glass reflector. If "F.R.A.S." can give me further test objects, I shall be greatly obliged.

If such men as Mr. Edward Henri Todé (who started, and for some time edited that journal), and who afterwards started and edited the Fenian), and others like him, cannot be induced on moral grounds to forbear from publishing their filthy broadsheets, it is time for the law to interfere. I trust therefore you will allow these few lines to appear, that now, when there seems a chance of the matter being agitated, we, who are represented by you, may not incur the reproach of having remained silent. KAPPA.

TEST OBJECTS.

There is no reason why every village church, if it has a bell, should not have a good public clock. A clever blacksmith, with a lathe and slide rest, could put such a clock as I have described, up in almost any town, for £25, if it only struck the hour, and make very good wages. The bearings for the spindles, I forgot to mention, were flat bars of iron, screwed to the wooden frames. The pivots work in brasses, rivetted in the bars. The pallets are made of sheet brass, and the 'scape wheel of steel. The pendulum bob is a cylinder of lead, weighing 15lb.

SYDNEY MADDISON, Hastings.
P.S.-I have no objection to indicating the place
where the clock may be seen; Partney, near Spilsby,
is the village, and the blacksmith who has charge of
the clock would no doubt be glad to show it to any
one who found it worth his while to go there.

I was engaged previously in putting up, in the tower
WILLIAM BAGULEY. of a friend's church machinery to strike the quarters

so as to keep the wick distended, which will then hang

down to the bottom of the bottle. Pour in about halfa pint of benzole, not rectified, but what is sold as ordinary benzole by chemists, at about 18. 6d. a pint. Then close the bottle, and connect the inlet pipe to a gas branch (after taking off the burner), and connect the end of the outlet pipe with the pipe leading to both lanterns. This latter connection must not be of india-rubber tubing, but either compo. or flexible tubing (to be got at all gasfitters), as the india-rubl

been once broken and the sod rotted. It is not adapted | material may be mixed in proportion, as we may wish
to breaking prairie or meadow land, nor for land that to make a more or less bulky kind of fodder.
is not comparatively free from stones, stumps, and JOHN HUGHES, Analyst, 16, Penn-road-villas,
Holloway, N.

NEW CARRIAGE BRAKE. SIR,-In your excellent journal of the 28th of January last there appears a notice of a new carriage brake. On reading the description of it, I was much surprised to find that a carriage or cart brake exactly The teeth or tines of the fork are cast steel, self-similar in every way to that now patented by Messrs. sharpeners, of the simplest possible form, 8in. in Parry and McHardy was exhibited at the show of the length, and are secured to the bar by a clamp, or Highland and Agricultural Society of Scotland held at stirrup, and wedge, and can be taken off or put on in Dumfries in the summer of 1860, and that to it was the field by any person, as each tine and stirrup will awarded a premium of £10. It attracted great attenfit the fork-bar of any sized spader. Great care has tion, and was universally approved of. It was made been exercised in determining the strength necessary and shown by Mr. Thos. M'Cririck, agricultural in these parts; but if broken, and no extras are at implement maker, Old Cumnock, Ayrshire, who has hand, may be replaced by any good blacksmith. A team in ploughing a furrow one foot in width long been well and widely known in the south and west of Scotland for his many useful improvements travels 8 miles to each acre (besides turning corners), and ingenious and original inventions in connection or 16 miles in ploughing two acres, which is a good with agricultural machinery, but whose diffidence of day's work for both team and man, and is not always disposition (which is so frequently found allied to true well done with a furrow of that width; if a narrower and original genius) has hitherto kept him from one is turned, the travel is increased. The five tine patenting any of his many inventions; and as he has spader works three feet in width; therefore six acres Dow considerably passed the allotted span of threeare spaded to 16 miles travelled, or as much as three score years and ten his career as an inventor may be pair of horses, three ploughs, and three men will do: said to be over. Still it is right that he should not be and but 275 miles of the team is required to spade 100 robbed of any honour which justly belongs to him; acres; making a garden bed of the grain-field at less and undoubtedly he is the original inventor of "the than half the cost of ploughing; and this may be done new carriage brake" described in your journal of the by any one able to sit on an easy seat and drive the above date. Messrs. Parry and McHardy may not team-no walking or other labour required. have seen Mr. M'Cririck's brake, and they may have been original inventors also; but even if such has been the case, they have been forestalled in it by Mr. M'Cririck by nearly ten years.

A photograph of the brake, and of the cart to which it was attached was taken at the time. Could we have obtained a spare one, we would have enclosed it; and we may do so yet, when more of them are taken. A. B. TODD, Old Cumnock, Ayrshire.

SIR, The ENGLISH MECHANIC of the 1st April, 1870, has just come to hand, in which I have noticed a letter that bears the initials of "S. B.," who says he was in hopes that some of your "qualified" correspondents would have answered "Veritas." because a fraction is a part only of a whole. It

"The I-005998 is a fraction." This is not the case,

"S. B." had stated that 1005998 was the proportion, ratio, or quotient of two distances or values, he would have been nearer the truth.

Mr. S. B." has one fundamental error in his calculation of the mean diameter of the sun-namely, he whereas, he ought to have used the mean semi-diameemploys the equatorial semi-diameter of the earth, ter in order to arrive at a mean value of the sun's diameter.

I beg to submit the following facts as given by
"F.R.A.S." and "8. B."
Miles.
845947
90854708
8"-91

It will thus appear that the values of "F.R.A.S." and "S. B." are wide apart.

Perhaps the best that could be done under the circumstances of the case is to appoint a scientific pope for the purpose of a final settlement of our scientific differences. VERITAS.

BOOKBINDER'S CUTTING PRESS. SIR,-I send a sketch of a bookbinder's cutting press, although I firmly believe it will be "Love's labour lost," for those whose trade it is to provide book binders with cutting presses do not always turn out a good press; but as Maschil" and others have inquired about the apparatus, I thought it would perhaps be best for the interests of "our" MECHANIC to comply with their wishes. Persons out of the trade seem to form the most erroneous ideas of bookbinding. gilding leather, &c. I should much like to see some

tightly fixed, which causes the cheek A to recede from or approach to the cheek B. GG are the heads of the two screws, through which are two holes, about of an inch in diam., in which the press-pin, or lever, which is about 20in. long, is inserted. HH are two strips of hard wood, placed about 1in. apart, for the plough to traverse .in. The cutting press here shown, is 2ft. between the screws. II are two guide rods, firmly fastened in the cheek B, which keep the cheek A in its proper position.

AB INITIO.

THE "ENGLISH" VELOCIPEDE ON A NEW PRINCIPLE, AND OUR ENGLISH ROADS. SIR,-For many years my attention has been directed to the subject of velocipedes, both theoretically and practically; and when your third volume was coming out I saw it was treated of therein, since which time I have been a subscriber.

The wheels, as will be seen in the drawing, are
rather small, the driving wheel being only 2ft. 8in.,
and the others 2ft. 4in. Some will very likely think
they are too small; but those who have made great
use of the velocipede on all kinds of roads will never
prefer them much larger.

The frame of this velocipede consists of angle Iron
bent in the forepart to a curve, as shown. It is filled
One end of
in with wood. They are in four parts.
each goes right across a strong board, to the under
Above this
part of which it is bolted by two bolts.
board is the seat, between which is the box, secured
by a lock and key. There are no springs, but a good
cushion on the seat, and I can affirm that I have not
experienced the slightest unpleasantness as regards
jolting, jogging, or shaking (I have gone over rough
roads); indeed, it is rather otherwise, for it is truly
comfortable to ride, as I have said above. Another
noticeable feature in this machine is the guiding han-
dles being placed at the sides of the seat. This allows
the chest more play, and gives greater opportunities
of development than when the hand has to reach fer-
ward to guide.

This latter remark leads me to refer to the worker
of the velocipede. It may be said that the velocipede
will never compete with the railway train as an econo-
miser of time. It may be so; but it can also be said
that the railway train will never compete with the
velocipede as a promoter of health. So the velocipede
question, in this respect, resolves itself into these
two points, time or health, not considering the saving
of railway fares. Time is no doubt valuable, but health
is still more so-it is invaluable; it is a fortune in
itself. What truly wise man would, for the sake of
his health? As vigorous health means greater capa
saving time, always avoid opportunities of promoting
bilities for business, it is questionable whether the
right use of the velocipede is not more favourable to
the attainment of wealth than otherwise.
I will conclude what I have to say on the question
in another letter, next week.

A THINKER.

The German

On the 15th

THE ENGLISH MEC HANIO. "An Old Subscriber" writes: "Allow me to congratulate you on the decided improvements recently made in the ENGLISH MECHANIC. Issuing the index with one of the numbers, separating the advertisement sheets from the body of the work, giving the contents on the outside page, increasing the size and at the same time improving the form of the publication, giving a list of the new patents -these, with what we have had before, combined with a greater variety of contents, and, I think, a certain sifting of the Notes and Queries department, make the ENGLISH MECHANIC AND MIRROR OF SCIENCE the principal scientific journal published. You need not stoop to the miserable and deceptive manœuvre of offering to give away prizes

for nothing,' in order to bolster up an artificial circulation; you can stand on your merits.

BENNETT'S DIE CHUCK -Edwin Baker writes:Will you allow me to correct an error in last week's number, with respect to Bennett's die chuck? Mr. Bennett invented and made that chuck while he was in the employ of the Messrs. Holtzapffel, and not Mr. Evans's, as it was given us to understand. I question if Mr. Bennett ever was in the employ of Mr. Evans at all,"

A GOOD RECIPE FOR HOME-MADE YEAST OR BARM.-Place a quart of malt in some wooden vessel, boil one ounce of hops in three quarts of water one hour; when clear from the vapour arising therefrom your over the malt so as just to scald it. Cover over with thick flannel or baize till morning, when it should have a frothy thead on; strain. Put half-apint of this liquid to 71b. flour, set your sponge over night, in the morning mix and bake in the ordinary way. This is an excellent recipe, and was given me by the late Sir Charles Napier's cook. Nothing can equal the sweetness of bread made from this.-W. I.

MEDICAL OPINION-Dr. Burdwenii in a letter says: "I love your MECHANIC, but I dislike to see medical questions, and often very absurd ones, asked through it. It is almost impossible to give an opinion without seeing the patient, and in most cases it would be dangerous to act on good avice given under such circumstances."

NAME OF STAR.-"Conjecto" writes:-"Allow me to thank Omicron (page 656) for the (probable) name of the star which I saw in conjunction with Venus on the evening of the 3rd Jan. I am somewhat surprised that no other mention has been made of this (to me) most interesting sight. I have watched many sented by Venus and this star, which I watched from occultations of stars by the moon, but have never been so pleased as with the beautiful appearance prethe early evening until they disappeared together behind the distant tree-tops. The star was at least as bright as Jupiter's 3rd satellite, and shone with a steadiness quite remarkable for a fixed star."

TO MAKE GOOD BARM.-"T. S. T." says:-" Boil loz. of good hops in 2 quarts of water an hour. When strained and milkwarm, add lb. of brown sugar and lb. of good mealy potatoes previously boiled and squeezed stone jar, and place by the fireside for one day and two nights. When it has done working put in a handful of salt, and cork the jar tight and place it in a cool corked after pouring any out. It is well to add a fresh place. This you may use immediately. Keep it closely for use when made six months. At about four o'clock quantity before the whole is used. It will keep as well set your barm-that is, get two or three potatoes (or one good large one), mash them up very fine, put them in a sieve and strain about three pints of lukewarm water over them into a crock (throw away the remainder), then throw the barm down on the top of this, then shake a couple of handfuls of flour on the top of this, and cover with a cloth and let stand before the fire till about 9 o'clock-by this time it will have risen, and fallen a little again. A regular quiet heat must be kept to it. At that hour throw a little salt through It should read 4810 square yards, being the flour, mix the barm well through the flour, and if too dry add a little warm water. Work it up until 69yds. 1ft. 10in. each way." Next morning, when "J. K. P." also writes:-"Under the above head-quite fit to put into the oven. well risen, divide into loaves (two quarts of flour to a ing, on page 23, you state a German mile at 1806 yards. loaf). After making the loaves, lay them on the board 'stunde or Now a German mile is what they call a hour, ie, an hour's walk, and Adcock's Pocket and cover with a cloth for about twenty minutes. Do Book gives 10126 yards, which agrees with Cham- not shake any flour on them at night after mixing the bers' Encyclopædia." Adcock states the Turkish mile barm in the evening. About fourteen quarts of flour at 1826, while you give 1626, and I have no means of to this much barm (three pints of made barm) -Buns telling which is right. A German short mile' is for breakfast: 1lb. of flour, whites of two eggs, 2oz. 6859 yards according to the Imperial Dictionary, and butter, two spoonsful of barm; mix together with milk to a light dough, put at the fire for one hour to is quite enough for an hour's walk for me." rise-five minutes will bake them. Mix as for a cake.'

I will be as brief and as plain as I can in what I am about to say, for my aim is the diffusion of clear views of the correct principles of velocipede construction, and to assist in its inauguration as a really useful machine. I have had several inachines made on different principles and designs. One, a three-wheeler, had two driving wheels, between which the rider sat. It could be worked up hill pretty well. Afterwards-thinking back, it would be easier to get up hill, I had one that if one were made for two to work, sitting back to very reverse anticipated! Two could not possibly made for two; and what was the result? Why, the work it up anything like a hill, and, strange to say, one could! This was about two years ago, since which time I have endeavoured to trace the reason of this; and about twelve months since I succeeded in what I thought might be some explanation of it. Suppose a man had to take two sack-loads of potatoes (weighing, say 5cwt.) a mile, and he had before him the choice of a wheelbarrow and a truck (a two-wheel handcart) to take them with; and granting that the truck weighs EXTRACTS FROM CORRESPONDENCE. as light as the wheelbarrow, which should we suppose he would choose? Common sense would say the INTERESTING FACTS." Pneuma" writes as truck, because he could balance the load on it, and all he would have to do would be to roll or wheel it follows:-" In your number for March 25, page 23, along. In the case of a wheelbarrow, he would have is a small paragraph headed Interesting Facts, to lift half the load before he could wheel the other among which are two or three statements which half. Now, as wheeling a load is easier than carrying perhaps you will allow me to correct. a load, it is evident that the wheelbarrow is a foolish mile is much more than 1800 yards. The German vehicle where a truck can be used. Let us look again short mile is 6859 English yards, and the German long at the above velocipede. We see that the spokes of mile 10126 English yards, and the Hanoverian mile the driving wheels act similarly to a man's legs in a 11559 yards (see Kelly's 'Cambist'). The greatest wheelbarrow, with this difference, that whereas in a depth of the sea is more than 4 miles. wheelbarrow a man's legs have only to overcome the November, 1849, Lieutenant (now Captain) Maury, in friction of half the load, in this machine the wheels the 'Fancy,' let out 5700 fathoms of line (about 6 miles) have to be made to overcome the friction of nearly the without finding a bottom. This was in lat. 31° 59' N. whole of the load before it can be moved. Again, let and long. 58° 43′ W. This depth exceeds the height of Mount Everest, in the Himalaya, by a mile. us now look at the truck. Its two wheels act as guid-statement respecting the English acre is evidently ing wheels, at the same time bearing the load, and the man's legs act as the spokes of a driving wheel. Now, if a velocipede were made on this principle, the question would be, Would it be easier to propel than the other? I was soon convinced that it would; and having proved it to my own satisfaction, I have laid down this maxim or principle as being the correct one in the construction of all velocipedes-viz., that no more weight should be placed on the driving wheel than is actually necessary for driving purposes. To illustrate this still further, take the case of a luggage train. Suppose that instead of the locomotive drawing its load of 200 tons behind it, the whole of the 200 tons were to be placed right over and upon DR. USSHER'S ADVICE.-Hy. Good sends us the the driving wheels of the engine, what would be the following." Will you allow me to point out one or consequence? Why, the power of any ordinary locoFirst of all, it two errors in 'Dr. Ussher's Advice?' motive would most probably fail in endeavouring to overcome the enormous friction caused by the load is not Dr. Ussher's, for I have now before me Cowabove. Observing the above principle, I designed per's Poems, in which I pasted a label more than the following velocipede, which at a glance will be thirty years since, a copy of which I enclose. perceived to be self-adjusting as regards the load on quite sure that it is an oversight of the doctor to the driving wheel. It also meets every other require'For oft-imparted knowledge doth ment that is looked for in the velocipede-viz.: Diminish learning's store." 1st. It is light and simple in construction and working 2nd. It is perfectly safe, easy to work, and You will also observe that the words 'I often lent comfortable to ride. 3rd. It is easy to guide,' and with all the wheels being free of each other. it turns sharp corners. 4th. It has a minimum of friction consistent with a maximum of power, as both hands and feet would be used; but I never found it to require more than the use of one hand with the feet up the steepest hill, the driving wheels not slipping.

wrong.

The

I am

FREE SCHOOLS OF INDUSTRIAL ART.-A

say-plan is now before the Massachussets State Legislature, U.S., by which every town of a certain size will be compelled to maintain, in connection with its town school system, an evening school for education in "the industrial arts." These evening schools will be open two hours on five evenings in the week, with a competent master or mistress for every 25 pupils. Travelling loan collections of models andcasts of works of art and design are to be formed, the expense of which will be borne by the commonwealth. A monthly system of examinations is also proposed, with the exhibition of meritorious works.

should be it often lent.' If some of your subscribers
would get up a neat label of the above, either in litho-
graphy or photography, leaving a space for name, I
think they could find a sale for them."

"

"St. George'
VARNISHING THE VIOLIN.
writes:-"I find amber varnish to injure the tone of
the violin the least of any that I have tried."

REPLIES TO QUERIES.

[1908.-ETCHING RAZORS. - For H,SO, read H2SO4.-F. B. KNOX.

has not suffered from the malady from that day | The content may also be found by obtaining the solidity
to this.-ED. E. M.]
of the middle cylindrical part, then that of the semi-
circular ends, and adding the two results together;
but I think "A Diver will find the rule given above
more concise.-WILLIAM MOOR, Jun., Hetton Colliery.
[2097.J-STAINING WOOD BLACK-Boil lb.
of chip logwood in 2 quarts of water, add loz.
of pearl-as, and apply it hot to the work with
a brush. Then take lb. of logwood, boil it
before in 2 quarts of water, and add oz. of ver-
digris, and oz. of copperas; strain it off, put in
lb. of rusty steel filings, with

[1967.]-PESTLE AND MORTAR.-Sulphuric acid
is the best thing he can use.-A MECHANIC.
[1970]-VARNISH FOR IRON PATTERNS.
'N. L." gives an excellent reply to this query, but he
forgot to say that it was raw linseed oil that should be
used, brushed on like paint. Should the pattern be
required for almost immediate use, coal tar naphtha is
very good, and it dries quickly without heat.-METAL
HEAD,

3

16

this go

over the work a second time. Oil of vitriol diluted with water

and applied with a brush makes a good black stain.GUILLAUME.

[2098]-DISCONNECTING STEAM PIPES.-Putting brown paper between the flanges and the indiarubber washer will keep it from adhering to the iron. I have found this to answer well.-ABERDEEN MECHANIC.

[2098.]-DISCONNECTING STEAM PIPES.-Canvas steeped in red lead is frequently used instead of india rubber; or if the flanges have been faced, a little plain red lead will do. Another way-Steep plaited gasket in whitelead, and by working it in the hand it may be used several times; or, instead of whitelead mix blacklead with boiling oil into a paste and work well into the gasket; if the flanges are rough or uneven, equal parts of redlead and whitelead with fine metal borings. In using gasket, canvas, &c., care should be taken that the ends do not overlap, but meet nicely.

ZINC PLANT. In reply to "Saul Rymea's"
question to me, his idea of the rationale is correct.
All the descriptions given relate to the lead tree, and
of course the more lead salt there is in the water the
more vigorous will be the growth of this specimen of
metallic growth. A true zinc tree would require the
use of a more oxidisable metal in a zinc solution, and
as the action of such metals as magnesium, sodium,
&c., would probably be too rapid, the metal would be
more likely to be thrown down as a non-adherent [2007]-TEMPERING DRILLS. Surely your
powder than as coherent crystals. The process is a printer must have misread S. T.'s" answer, which
true electric one when the "plant" is formed, the is exactly the opposite to what he must have meant to
electricity acting at the extremities of each deposited state, and which, so far from hardening drills, would
particle, and producing there the crystalline deposit. anneal and soften them. Let me add to my former
Other metals may be thus deposited aleo, and the reply to this query: That for small drills, say to
nearer alike the affinities of the two metals are for the
acid holding the one in solution the slower and more-in. diameter, a candle is the most convenient
perfect the action.-SIGMA.
[1708]-HEATING GREENHOUSES BY GAS.-means of letting down the temper, as the mild heat
causes the colour to change so gradually that the exact
tint can be obtained with certainty.-J. B.
[2013.]-MULTITUBULAR BOILERS.-Tubes ia
boilers of this kind should have a ring on one end, say
in. thick; the ring may be put in the end of the
boiler first, and caulked. In ordering the tubes, he
could order them bulged at the factory, about 1-16in.
The advantage of the ring is that if the tubes should
scale they can be knocked out from one end.-MILLY.-BLUE RUIN.
[2043,]-PILLS.-Not only pills, but (that most
nauseous form of medicine) powders may be taken by
any one without the least difficulty. Buy at any con-
fectioner's a sheet of the wafer that they use for rati-
fees, costing one halfpenny. This is 8 or 9in. sq, and
is to be broken up into squares of an inch and half or
two inches. Take one of these, dip it in water, and
lay it on the palm of the hand, where it instantly
becomes as limp as a rag and as slippery as an oyster.
Lay your one or more pills, or your powders, in the
centre, and fold the wafer over it, put it on the tongue
where it lies flat, like an oyster, and a sup of water
takes it down without taste or trouble. This method
is always practised in Germany, and has been in use
in my house for twenty years, and, strange to say, I
have never met any person, medical man, or druggist
in England who seemed to have ever heard of it. It
is perfectly effective, within reach of the poorest, and
ought to be more generally known.-G. NASH, S.
Michael's Vicarage, Louth.

In reply to "Professional," p. 637, I beg to say that I
shall be glad indeed if he can point out a plan by which
gas may be used in the heating of greenhouses, so that
it may be done with some degree of economy. He has,
however, a much better chance of doing so than I have,
as with him gas is charged 3s. 6d. per 1000ft, but with
me it is 68. 3d., in itself a mighty difference. I have
long thought that our gas company is extortionate,
but they maintain that the superior quality of their
gas, made from Cannel coal, makes it as cheap to the
consumer as gas from other coal at half the price.
This reasoning may suit their dividend of 10 per cent.
per annum and a bonus besides, but I must acknowledge
I don't believe in it. "Professional" suggests that it
may be the arrangement, and not the material, which
causes the failure with me. I shall endeavour as
briefly as I can to explain my apparatus, and then he
may judge for himself. It consists of a small copper
boller connected to about 64ft. of 3in. iron pipe. The
boiler is a cylinder, the under end, as it were, pressed
in to form a concave for the flames to play upon. En-
veloping the boiler is an iron jacket allowing a space
of about 2in. between it and boiler. From the top of
the iron jacket a 31n. iron flue is carried away so as to
take off the fumes of the burnt gas, and also to radiate
as much heat as possible. This flue is carried the
whole length of the house, and then passed outside.
The gas is applied at the bottom of the boiler by three
of Buusen's burners, so arranged that either one, two,
or three may be lighted at one time. I find that in
severe weather it required the whole to be lighted,
and on these occasions, supposing they were lighted at
at 4 o'clock in the afternoon, and were kept burning
until 8 o'clock next morning-16 hours-it consumed
about 400ft. of gas, which cost me 2s. 6d. The apparatus
worked well and gave little or no trouble; the only
drawbacks were want of heating power, except a very
large quantity of gas was consumed, and the injurious
effects the fumes had upon the plants. This latter objec-
tion could be remedied by keeping the gas entirely out
of the house, but this would necessarily entail a cer-
tain amount of loss of heat, which could only be made
úp by a greater consumption of gas. I suspect others
have come to the same conclusion as I have done (I
notice the reply of "J. B.," p. 12, vol II., &c.), but if
"Professional" can preduce a plan by which gas may-Seeing no one answer T Harding, I will endeavour
be used with a reasonable cost, and at the same time
to give a sufficiency of heat, I am sure he would confer
a favour on several of us amateurs, as there is no
doubt that the little attention gas requires gives it in
that respect a great advantage over other modes of
heating. AMATEUR,

[2044.]-REPOLISHING STEEL WATCH CHAIN. -"H. B.M." should rub his chain between his hands, dusting them with fine flour of emery from time to time; he will soon get it tolerably bright, then fasten it to his bunch of keys which he carries in his pocket, and the chain will soon become burnished, Proved. -F. H.

[2055]-COIN OR COUNTER.-My statement on p. 20 is incorrect; as stated by Mr. Batty, the pieces referred to are certainly weights.-HENRY W. HENFREY, M.N S., &c., &c.

[2059.]-CEMENT FOR AQUARIUM.-1 India-
rubber, 12 mineral naphtha or coal tar heated together,
add 20 of pounded shellac. When required to be used
heat to about 2609.-BLUE RUIN.

[2062.]-SODA WATER BOTTLING MACHINE.
to do so myself. In the first place his leathers are too
thin, and the hole in the washer should not be smaller
than the cone where the corks are put in; again, have
them serewed up tight. I have been in the habit of
buying a soldier's belt (an old one), and making them
myself. One lasts me nearly two years. Since I have
used them, now nearly ten years, I have never had the
bother T. H. complains of If he wants any further
information, I shall be glad to give it.-J. T. BAILEY.
[2038.]-CONTENT OF IRON PANS.-In auswer
to "J. R. W.," taking the depth of the pan as h,
diameter as d, and V as cubical content of pau,

[2110] TO REMOVE RUST.-Plunge the hooks into a bath of diluted hydrochlorie (muriatic) acid, say 1 pint of acid to 1 quart of water. Leave them there for twenty-four hours, then take them out and rub them well with a scrubbing brush. The oxide will come off like dirt under the action of soap. Shoult any rust still remain, as it is likely in the corroded parts, return the hooks to the bath a few hours more, and repeat scrubbing. Afterwards well wash in plain water several times and thoroughly dry before a fire. Lastly, a little rubbing with oil and fine emery powder will restore the polish. Should grease have mingled with the rust, it is necessary to remove it with a hot solution of soda, before submitting the metal to the acid.-GUILLAUME.

[2116.]-WATER POWER.-I find that my answer to this question last week had reference to 200 cubic feet of water per minute falling from a height of 30ft.. whereas the question was: What would be the power of 200 gallons per minute falling from that height? The answer should have been 14 h. p., reduced to a useful effect of 1-h.p.-C. S.

1

6

[2117]-CEMENT FOR IRON ROOM.-" T. S. H." will find the following to answer his purpose: 1 bushel of sand, 4lb. of red lead, llb. of whiting; mix up with boiled linseed oil and a little boiling water.-SWEEP Ho.

[2119.]-CLEANING PIANO KEYS AND TEETH. -If the discolouration does not extend much below like its original condition is obtained, then smoothed the surface, the ivory may be scraped till something with very fine glass paper, aud finally polished with a leather buff and whiting. As to teeth, if "Ilex" means natural ones, which have simply obeyed the laws of nature, I with him should be glad to know of any to their present or future usefulness, but such a remedy means to restore their pristine whiteness without injury I fear, will be as easily obtained as a mill for grinding old age into youth.-F. F. C.

[1820]-HOW GLASS FOR CHURCH WINDOWS IS FIRED.-When the windows are painted with the requisite colours, they are placed in an oven much resembling the ordinary bakehouse oven. Around this oven are iron shelves, upon which are placed large iron plates very level; on these plates the glass from the windows is placed; the oven is then very gradually heated. The beat is adapted to the nature of the colour required; if the flux is hard the heat is much greater than when soft. This requires great nicety, and perfection can only result from much practice. It sometimes happens that one or two moments of too Again, cubical content of globe, taking d = diameter chisel-and apply to J. Blakeborough for a patent tap,

prolonged an heat, will spoil an entire batch of window
panes, turning the colour from what was intended as
a bright yellow, to a dirty brown. When the oven is
got to the required heat, the calculation is made by
the man who has charge of it as to the duration of
the heat; this is very carefully watched, then when
the glass has had sufficient fire, the oven is stopped up,
the bars from the grate drawn out, and the whole is
left to cool gradually to prevent cracking. When cool
they are then washed with water, the ochre comes off,
the beautiful stain remains. The heat required is a
little over that of redness, just approaching a white
heat, but modified according to the nature of the
colouring materials.-JOSEPH LEICESTER.
[1871.]-BLOTCHY FACE.-I have just perused Mr.
Johnson's reply as above, in answer to a "Sufferer
from Blotchy Face." It is certainly good sound ad-
vice, but not a remedy for this disagreeable ailment.
Four years back, having been troubled with it in a
violent form, I was induced to pay a visit to the late
Dr. James Seaton Smith, of Liverpool, surgeon of the
Skin and Cancer Hospital in that town, for the pur-
pose of getting a remedy for it. His remedy was the
enclosed, coupled with good and plain diet, which
put me to rights in two months. The recipe was
dear (£2 28.), but it was effectual. Let the gentleman
interested give it a trial, and kindly let me know the
results through your columns. Sol. arsenic chlorid,
1dr.; tinct. ferri perchlorid. 1dr.; tinct. rhu. 2dr.;
lig. zarafar 4dr.; aq. pur. 12oz. Ointment-Megt.
plumb, iodid. 11dr.; to be applied outwardly.-FORTU-
NATUS.-[A friend of ours, many years since, was
troubled with pimples on his face, and particularly
under his eyebrows and moustaches. He consulted
several country doctors without deriving any benefit.
He tried the hydropathic treatment, with the same
result. He came to London, and consulted one of the
physicians of the Cutaneous Hospital, Bridge-street.
Blackfriars, and was cured in about a fortnight; and

=3·1416.

= ... V

V cubical content

π

6

(3d 2h) h2

BLUE RUIN.
[2084.]-GRANITIC PAINT.-"S. T.," in his reply
in your last week's number, is in error as to this paint.
He states that the menstruum employed in it is silicate
of potash, to harden and combine it with the pigment
with which it is admixed. The granitic paint of the
Silicate Zopissa Composition and Granitic Paint Com-
pany, of 39A, King William-street, City, contains no
silicate of potash, and is well known to dry and harden
in a manner superior to any paint yet manufactured.
The statement of "S. T.," if uncontradicted, might
do us great injury.-THOMAS CHILD, Manager.
[2093.]-BRAZING CAST IRON.-The only method
of brazing cast iron is to fit the broken parts exactly
together in moulding sand, then pour melted iron
over the parts to be joined, and when cool chip off
the superfluous iron. If properly done the joints will
be difficult to detect -BLUE RUIN.

[2094.]-SUBMARINE LAMP, &c.-I send the fol-
lowing reply to the second question of "A Diver,'
under this heading, viz., to find the solid contents of a
vessel with semicircular ends:-
Let Full length of vessel

d Diameter

39

8 = Solidity

s = d x 2618 (3d),

From three times the total length of vessel subtract
its diameter, multiply the result by the square of the
diameter and by 2618 for the solidity.

If = 10ft., and d = 4ft., we have
16 x 2618 (30 - 4)

= 16 x 2048 × 26

= 108 9088 cubic feet.

[2121.]-BOILER TAP. Had "Gilder" followed the suggestion of some of our correspondents, adding oil. It will not stop the leaking, but make the tap use"proved," he could not have recommended emery and less. Let" R. A." pound a piece of freestone, and sift it through a piece of coarse packsheet. Mix this with water and grind it, adding no sand, but keeping the plug wet for five minutes before drying the plug and bill. This, if properly done, will make the tap perfectly tight. Proved-CONICAL PLUG. [2121]-BOILER TAP-I should advise "R. A." to take his tap out-he may do so with a hammer and which he may fix himself. It will not leak for years; and then it can be made good without taking it off. Address J. Blakeborough, Commercial Brassworks, Brighouse. Yorkshire.-SWEEP HO.

[2126.]-JOINING WIRE.-" E. H. B." will make the best connection by first cleaning or scraping with

an old knife three or four inches of the wire ends; cross them at right angles, hold firm with a pair of pliers, and twist the ends tight around each other; then solder with rosin.-SWEEP Ho.

[2131.]-PUMPS.-In reply to Plumber," although this does not seem to me to be plumber's work, a turbine may be made to receive a supply of from 40 to 50 gallons per minute (say 45) with a fall of 8ft, and to deliver water at a height of 70ft. above it at the rate of 3 gallons per minute. This is a small quantity, but it is as much as can be done with the power and under the circumstances named, A water ram would be a more suitable appliance, and would cost less. would deliver about the same quantity.-C. S.

It

[2139.]-BOILER.-If John Jones will state, through the MECHANIC, the length and diameter of the boiler he intends to put down, and what is the greatest height he can put his water-tank from his steam boiler, and the pressure of steam at its highest point, I will send him a rough sketch of a self-acting feed that I have at work at present on two boilers working at 15lb. per square inch -ANTI-EGYPTIAN.

[2143.]-SOFTENING CAST IRON.“ G. B. K. cannot soften cast iron. But by chipping off the surface or skin with a chisel he will find it easier to cut -BLUE RUIN.

[2152.]-PAINT ON BICYCLES.-Grind the dry colour; thicken with good pale copal varnish, then thin with turpentine; lay on evenly with common paint brush. This should have very dull appearance, and dry very hard. When thoroughly dry, varnish with good pale copal (or carriage) varnish; put in a warm

place, and away from dust (after varnishing), until thoroughly dry.-W. H.

[2160)-PRESSURE ON COLUMNS.-If"W. R. E." will give the length of columns, and state whether they are composed of cast or wrought iron, I shall be happy to answer him.-BLUE RUIN.

(2100)-PRESSURE ON COLUMNS.-This question cannot be completely answered in its present following figures, from the Engineer's Pocket Book," form, as the weight of the columns is not given. The may, perhaps, suffice:-Solid cast-iron columns, 34in. diameter, will each bearHeight in feet | 6 1 8 10 1 12 14 16 Load in cwts. | 282 214 | 191 | 172 | 156 -J. B.

136

[2160]-PRESSURE ON COLUMNS.-According to Molesworth, the breaking-load distributed equally on 34

376

[2183.]-TAXIDERMY.-There are a few chapters on the above, as well as on skinning and preserving birds, reptiles, fishes, &c., at the end of "Beeton's Book of Birds," which may be ordered through any bookseller.-VIVIS SPERANDUM.

[218] SULPHATE OF LEAD BATTERY.Some time ago I decided to fit up my house with some half a dozen electric bells. I got all the apparatus I but took some time to consider this matter, as I wanted required from a firm at Halifax, except the battery. one which would fulfil two conditions-cheapness and constancy. I at last decided upon a sulphate of lead, one which I must say has answered perfectly both. I made it up myself as follows:-I obtained 6 glass pickle jars and 6 porous cells, I then made 6 cylinders of thick sheet zinc to go easily into the glass cells. I got some No. 8 copper wire and wound into spirals to fit loosely into the porous pots. After placing them all in their proper places I mixed up some sulphate of lead with water and nearly filled each porous pot. I all four columns = 596- whereby L is the length then filled each glass cell within an inch and a half of the top with clean water, adding some crystals of Tidman's sea salt, and after connecting the copper spirals of the one cell to the zinc cylinders of the next all through the series, leaving a zinc unconnected at one end and a copper unconnected at the other end, it was all ready for use. I placed it upon a shelf at the top of my cellar and connected the wires communicating with my six rooms and bells. It is now nine months since it was set going and appears as good now as at first. It cost me for material about 153,, the cells are quart size, I am very proud of my handiwork, and believe it quite as good and far cheaper than the trade would have supplied me.-A GOOD BOY.

L

17

of a column, assuming L to be greater than 15 times
the diameter of the column. The calculation is easily
carried out by means of logarithms.-A. TOLHAUSEN.
[2162]-SEAMS OF MACKINTOSH.-If "G. W. D."
will refer to reply 1777, page 613, Vol. X., he will find
that 1 there stated that I found "Kay's Coaguline
(Kay, Bros., Stockport, 6d. per bottle) answer my
purpose in mending the seams of my mackintosh, which

statement I confirm.-W. H. I. P.

[2162-SEAMS OF MACINTOSH.-Nothing is better than india rubber dissolved in naphtha.-J. B. [2169]-PROBLEM.-Through A draw A F parallel

B

H

But since BH

have sometimes to wait a considerable time, I generally manage to get what I am in search of.-H. B. MILLER.

12215.]-BRONZING BRASS.-Some time since, I asked through these columns how to bronze the ferrules of fishing rods, without eliciting any reply, I fortunately found a tradesman who kindly told me, and I succeeded perfectly in giving the brass an appearchloric acid. Clean the brass well to get rid of lacquer ance of real bronze. The recipe is, ld. of oxide of iron (rust), 1d. of arsenic, mixed in a pint of hydroor grease, and apply with a brush until the desired colour is obtained. Stop the process by oiling well, when it may be varnished or clear lacquered.-VIVIS

SPERANDUM.

[2218.]-GEOMETRY.-Theor.: three circles being given, the lines respectively tangent to 2 of them bave their intersections on the same straight line. "X. X." asks a geometrical proof: perhaps the following Draw a plane through the 2 might satisfy him. centres; on each side of this plane we can construct one tangent to the 3 spheres constructed on the circles; these 2 symmetrical planes will cut the plane of the centres on the same line. Now, supposing 3 cones respectively tangent to 2 spheres, those 3 cones will be langent to the 2 planes, and have their vertices on their line of intersection, and those vertices are the intersections of the tangents to the circles. Other demonstration, Analytic, v. Salmon, "Conic Sections," No. 117.BERNARDIN.

(2220)-SOLDERING.-File the end of the iron pipe

bright, then see that the soldering iron (which should
be as large a one as can be got, so that it may carry a
great amount of heat) is well tinned; this is important
in all soldering operations. When the iron has been in
use some time after tinning, or when it has been made
too hot, the solder and the copper become melted
together and the solder seems to eat holes in the copper.
In this state the iron is not fit for use, but must be
Having the iron
filed down smooth and re-tinned.
ready, and as hot as it will bear, take and wet the
part to be tinned with a little spirits of salt that has
had as much zinc chippings put in it as it will dissolve,
then apply the solder with the iron, bearing in mind
that the pipe will have to be very hot with the iron
before it will tin; it would be as well to tin the iron
pipe with a little block tin or pewter, if available. If
any difficulty is found in tinning the iron pipe a little
powdered salammoniac might be sprinkled over it
when very hot, which would assist the tinning; this
done, the lead pipe must be widened out so as to form a
lip all round the iron pipe, and soldered round with
fine solder,taking care to keep the heat of the iron on
quantity
the iron pipe rather than the lead, or what is called a
plumber's joint may be made by pouring on
of plumbers' solder from a ladle, and wiping off the
superfluous solder with a greased cloth. For an
amateur the first plan will be the most simple.-
SIGISMUND.

to BC, and equal to the difference between A C and
AB. Join C and F, and produce C F and A B to meet
in G. Bisect & Cin H, and join G H by a line cutting
Ain E. Through E draw DEI parallel to BC, and
DF is the required line. For since A FAC-AB,
and the triangles ACF and E C I are similar, as also
ADE and ABC, EI EC-DB.
The C, and D I is parallel to B C DE EI.
Then D E EC - DB as required.-T. BROWN.
[21701-AN UNANSWERED QUERY.-I beg to
inform "Gitche Manito" that I replied to this question
some time ago. It is the opinion of the best numis-
most that copper coins should be left alone, or at
most simply washed with soap and water. Cleaned or
Wured copper coins are quite worthless-HENRY
WHENFREY, M.N.S., &c., &c., Markham House,
Brighton.
quantity of corrosive sublimate in vinegar; dip or
(2170)-UNANSWERED QUERY-Dissolve small
blacklead, using common stove brush.-W. H.
Place copper coins therein; wipe dry, and finish with
"Fan Blast
176-BLAST FAN.-The proportions I sent
(p. 563, Vol. X.) are suitable for a smith's
forge. Let "CT" look at them, and if he cannot get
on with them I shall be very glad to help him all that lamp; that is to say, it is to stand upon the gallery and VIVIS SPERANDUM.

[2188.-VELOCIPEDES, &c.- In every case a
driving wheel above 36in. becomes a disadvantage; the
greater the diameter of the wheel above 36in. the
greater the disadvantage. Treading is the best mode
of driving, for when the foot is pressed on the treadle
the weight of body then ceases to be the load and be-
comes the propelling power. As a crank 6in. in depth
is quite sufficient for working the foot, so a driving wheel
more than 36in. will be too great a leverage for that
crank; and what is gained by a larger wheel
down an incline is lost with more when on a bad road
or ascending a hill. Sit as close to the driving wheel
as possible, that the pressure may be on it; enough
pressure on the guiding wheel to steady it is sufficient.
Regulate the height of your seat according to the
on
depth of your treadle, so that when you are
your seat, and your legs straightened down, the
foot may just fairly reach the treadle when it is at its
extreme downwards. I would use two connecting
rods-one on each side. Let them be your treadles,
pivot them to the crank of the driving wheel (the hind
One), also to the crank through the frame between the
wheels. Let each crank be of equal length that the
treadles may work in unison-oue handle to guide
with, another for the brake; also a projecting bit
close by the brake handle to steady yourself with (this
is for driving the hind wheel). Perhaps you may glean
something from these suggestions. I think we may
yet improve the veloce. I have been a velocipedist
more than 20 years, and I consider as yet it has been
altered and not improved. The bicycle is fit for none
but those who are fond of dangerous sports. Driving
the front wheel of a tricycle, sitting so far from it,
and dragging two behind, it is a mistake. Driving
by levers pivoted near the front wheel is a mistake.
A four-wheeled veloce is the best.-N. G. LAMBORNE.
[2195.]-SMOKELESS LAMPS.-I beg to inform
"Practical" that the cone must be made to fit the
reach up to that part of the wick just going to burn,
(2178.)-CIRCULAR DISC.-Areas of circles vary leaving an air passage at top abou: à free, as shown in
square of 6in. (the radius of the given circle), the radius
the squares of their radii: as, therefore, 36 is the my section, page 459. It must, moreover, be adjusted
of the disc which is to cover half the area must be the
to each lamp so as to produce the best effect. The
ball should be about the diameter of the round wick,
square root of 18, or 4-2426407in.-J. B.
also adjustable as to height for best effect. Hollow
[2178]-CIRCULAR DISC-If "Indagator" will
balls of brass or iron may be got of the proper size at
inscribe a square in a circle of the diameter of the ori-
ary metal shop. The cone prevents the air passing
fice-viz., lft, the side of the square will be the
through the pierced bottom of the gallery getting into
diameter of the required discs = 84853in. Or, if he
the glass globe, and must not therefore be pierced.
will square the diameter of the orifice, 12in. x 12in =
For raising and lowering the wick, Practieal" must
144; take half the product 72in., extract its square
look at any well make round wick colza lamp, or,
t=84853in. because the areas of circles are touch argand burner. Upon the whole, as "Practical" does
other as the squares of their diameter.-S. B.
not seem to be well acquainted with this subject, I
[2180.]-ENGINEERING IN GERMANY.-There
should advise him to apply to a practical lamp manu-
are several engineering colleges-Polytechnische HENRY W. REVELEY, Reading.
facturer who will at once understand my section.-
Schulen-on the Continent that have attained a world-
wide fame. In these colleges very little knowledge
[2200.]-STEAM LAUNCH.-An engine working up
of mathematics is required to the examination
to 8-horse would be about the power required for the
on the preliminary course-Vorschule-dinator boat mentioned by Solicitor." I should recommend a
or five years' study the student can have gone through
vertical boiler for two reasons. Firstly, they are much
the various branches of engineering, theoretically and
and dilly, the latter shown by excursions, it steady
and diligent. Age required. 17, and yearly school fey,
Karlsstablishments of this kind exist in Berlin,
Karlsruhe, Hanover, Munich, Stuttgart, Vienna,
Zurich, &c. Should any young gentleman
information. Lastly, the x area of the sector is =
the idea of studying there, I can give him entertain
Ma square feet.-A. TOLHAUSEN, 18, Waterloo-road,
Manchester.

I can.-JOHN W. BEDFORD.

more convenient to get at for cleaning and repairs—a
most important point where salt water only is used;
and, secondly, the tubes are not so likely to be un-
covered by the water in consequence of the pitching of
the boat in a rough sea. The boiler should be made of
the best material and capable of standing at least 80lb.
working pressure. The engines should have double
cylinders and be fitted with reversing gear. Is not 9ft.
beam rather to much for a boat only 36ft. long?
About 7ft., I should say, would be a better proposition.
I shall be happy to give" Solicitor" any further in-
formation should he require it.-CANON.

[2224]-BOILER.-In reply to inquiries from "One in a Fix" respecting the use of Carrigeen moss to prevent the incrustation of boilers, I was recommended reason why it should not be put in feed cistern and

to use it by an inspector of boilers. I do not see any drawn directly to boiler, provided there is no overflow from cistern that would carry off the moss as waste. The quantity I would recommend for 50-horse boiler would be a stone weight per week (the present cost of the moss is about £10 per ton here in Ireland). I cannot speak of its merits as a purgative of a very foul boiler, as I never allow a scale to get on mine; but I do think from using it that it prevents the formation, and I am certain that it is a very harmless article.

[2225.]-VACUUM IN CYLINDER.-The exhaust

steam leaving a high pressure cylinder causes no vacuum, but, on the contrary, should the passage be too small it often causes back prefsure and compression on the return stroke by not fully and easily exhausting.-H. SUMNER.

[2227.]-LIFE PRESERVERS.-The life preservers found on all sea-going vessels are composed of slices of cork, neatly arranged and compressed together so as to form a zone 30" in diameter, 6" in width, and 4′′ in thickness; it contains about 12lb. of cork, is generally covered with painted canvas, and will support 6 persons. Inflated belts are liable to get punctured, and so tendered useless.-VIVIS SPERANDUM. [2227.]-LIFE-BELT.-" Avalonensis" would find Aquatic "the buoyant waistcoat" made by the Safety Company "better for boating than any of the ordinary life belts. My friends say they are the best and most portable things of the kind yet out.W. H. I. P.

[2228.] ADDRESSES WANTED. If "Foreign Correspondent" will get the Mineral Statistics of Great Britain and Ireland," by Robert Hunt, F.R.S., published by Longmans, Green, Reader, and Dyer, and by Stanford, Charing-cross, price 2s., he will find the name of every colliery in the United Kingdom and where situated, and owner's name, besides & quantity of other useful information.-S. W. T.

[2233.]-STAINED GLASS.-A small treatise on "Glass" is contained in Vol. 115 of Lardner's "Cabinet

(2182)-CONSTRUCTING COILS." Nemo" will Cyclopædia:" after this, study the works of the late Charles Winston, to whom every glass painter is deeply for a coil the size he purposes making it would require about 40 yards of No. 16 primary wire; will [2204.]-PROBLEM.-If " W. B. S." considers his indebted for the untiring attention bestowed on this art, be better to use No. 12. The number of sheets or wil problem, he will see that it resolves itself into finding from 1830 until his lamented death in 1864. They printo the pound of course depends upon its thickness; the height of a cylinder of water weighing 25 lb., and cipally consist of "An Introduction to the Study of the best foil, however, runs about 60 sheets Ift. square standing on a circular base 12in, diameter. I think he Painted Glass, with Remarks on Modern Glass Paintto the pound. If the coil is well constructed the maxican work this. With regard to his second questioning." 1849, Parker; "Memoirs Illustrative of the Art of Glass Painting," 1865, Murray; "An Inquiry into mum spark will be about 6in. long. The number of the atmospheric pressure per inch which susbottle batteries requsite will depend on the surface of (2203); in. of mercury in the barometer is the weight the Difference of Style Observable in Ancient Glass carbon exposed: he will probably require five are of tai 35 30ubic inches of mercury, a table of specific Paintings, especially in England, with Hints on Glass The secondary wire should be first covered gravities will inform him that a cubic foot of mercury Painting," 2ud edition, 2 parts, 1867, Parker and Co. with silk and have some insulating material, in a fluid weighs about 136000z. From this he can calculate the "Proba est materia, si probum adhibeas artificem."Erasmus. I trust this reply may not prevent Mr. state, brushed over each layer as it is wound on the pressure required.-PNEUMA. coil. Thin paper saturated with paraffin wax may be substituted for gutta-percha tissue. The silk used for [2203.]-CERAMIC MANUFACTURE.-The treatise Leicester from rendering his highly-valued assistance. -H. B. MILLER. on porcelain in Lardner's "Cyclopædia," which may covering wire differs from ordinary silk in not being generally be bought at bookstalls for about 2s. 6d.. [2234.]-FROM "JUPITER."-My 3in. glass was twisted.-J. D. M. contains an account of the colours used in painting got from S. and B. Solomon's, 39, Albemarle-street, (2183.1 TAXIDERMY. Taxidermist's and printing. There are several editions of Brong- London; price, on pillar and claw-stand, £5. It has one Manual," &c., by Capt. Thomas Brown, F...mist' niart, but no cheap one. The way I pick up my books day eyepiece about 40 power, and one night-power lished by A. Fullarton and Co., London. Price 38. 6d. at a low price is by reading the catalogues of dealers 100, but I have added several others since-20, 60, 75, ?).-WILLING. in secondhand books, or sale catalogues; although I (100 day eye piece), 150 and 275. The latter works very

The