number of teeth. You will observe on the gauge. that to the right of the zero line, is a space containing two of the divisions, that there are to the left of the zero, and that quantity is the "addendum," or quantity that the outside of the wheel is bigger than the pitch diameter. So to find diameter of a wheel of 20 on the top scale of all, put one point of your compasses at 20, and measure towards the left as far as the zero, and that will be correct. Or for 25 teeth, measure from 20 past the zero to the number 5, including altogether 27 divisions, and that will be right. And the same for any other scale. It is to be remembered, in making the guage, that the 5 gauge is 5 parts to an inch, and the 10 gauge is 10 to an inch. A piece of the gauge 7in. wide and 6in. high, will be quite enough to show the principle. I must request care in using, as it is the original and only one I have.

SHORTHAND.

J. K. P.

practice of about one hour a-day for six months, and
having kept the dictation for more than two years was
able to read it with very little difficulty, although the
subject ("Locke on the Ideas ") could not enable me to
guess at any of it. Forty years of experience have
been required to bring this system to its present state
of perfection. No disadvantages can attend the know-
ledge of such a useful accomplishment as shorthand;
the many advantages are obvious.

Mr. Pitman's office is at No. 20, Paternoster-row,
E.C. Mr. Lewis's is at No. 113, Strand, W.C., where
Mr. Lewis will give all information at almost any
time. The former gentleman has published a small
inexpensive book on his system, and the latter a half-
guinea book on his system, which is used in both
Houses of Parliament and in the Courts of Law.
The Prayer Book and the New Testament may also be
had in Lewis's system. I think you will agree with me
that only those who can speak from experience ought
to express an opinion on the relative values of various
systems, no one profits by being told that some one has
heard that one particular system is the best.

64

FKANK W. GRIERSON.

SIR,-Your" Hermit," on page 255, wishes
for any information which I can give him, on the
merits of shorthand, and of its "different "
systems. Five-and-forty years ago I took up Sam
Taylor's system, which was published A.D. 1786. I
had also Wm. Mavor's, of 1789. This latter I did not
follow, for Wm. Harding's came out in 1832 with
Taylor's Improved," which I followed, with some
modifications, ever since, examining every novelty as
it came out, and comparing its merits with my old
adoption-improving it if I could.
Pitman's system is the only one I can call a rival of
Taylor's, and that only because of its many admirers.
learned it, tried it for some time, but abandoned it as
complex and unsatisfacty. It has but ten characters
for twenty letters, to be distinguished from one an-
other by their "thinness" or their " thickness."
Taylor's are all unlike, except where you can write one
letter for another, as for instance, S for C soft; G
for J, or rice versa.

I

I think" Hermit" could write freely from dictation in six months, by an hour's practice a day; and that in half that time, he could keep his diary and note-book, to his great contentment.

64

I would recommend "The Hermit " to write for the Phonographic Teacher," 6d., to Mr. Fredk. Pitman, Paternoster-row; "Stenography," by Thompson, 18., to Mr. Fredk. Warne and Co., Bedford-street, Covent Garden; "Taylor Improved," 8d., to Groomridge and Son, 5, Paternoster-row.-Compare them together, and make himself master of both alphabets and joining tables of these systems. When he comes to the end of that stage, I can tell him

SIR,-Having learnt three systems of shorthand, viz., Mackenzie's, Pittman's. and Lewis', at times sufficiently far apart not to mix one system with another, I have to state in answer to "Hermit" (who, by the, way, puts his question in the unusual form of a letter) on age 255, that, in my opinion, Mackenzie's is not worthy the name of shorthand, Pitman's one of the worst, and the Royal Lewisian system by far the best, beating all others hollow; the first two, I am thankful to say, have long departed from my memory. I have often written 110 words a minute in Lewis's system, and a friend of mine has written more; the most rapid reporters are said to be able to write 250 words a minute in it, but I much doubt any one's ability to do so in such a short time. A gentleman who has used Pitman's system for many years acknowledged, after trial with me, that the system I write (Lewis's) is the clearer and shorter of the two. As Mackenzie's system is now never heard of, there is no occasion to say anything about it. The great fault in Pitman's consists in using the same characters when made thick and thin to represent different letters; I have heard many writers of Pitman's system acknowledge, and have myself discovered that it is impossible to make any real difference in the thickness of the characters when attempting to write rapidly; the consequence is that unless the shorthand be transcribed while the subject is fresh in the memory it is practically illegible; but the most ridiculous feature in Pitman's is that there are (as nearly as I can remember) six different posi-20, tions for the vowels and dipthongs, so that when the writer finds it necessary to insert the vowels, as in a proper name, or foreign word, for instance, he has to consider while he is rapidly writing, first, what is the proper sign for his particular vowel, and then its proper position-whether it should be at the upper end on the left hand side of the character representing the nearest consonant to the vowel, or at the middle below the character, or at the upper end above the character, or at the lower end on the right hand side of the chaSPECULUM TESTING-THE " PHANTOM."racter, &c., &c., according to the position of the chaCALLAND'S BATTERY. racter on the paper; such consideration is almost impossible; rapid writers in Pitman's system are SIR,-Thinking it would interest many of our astroobliged to alter and improve it in this particular. Inomical friends, and having a little forced leisure remember I made out a kind of table to try to remem. upon my hands through being invalided by a serious ber the different positions. Anything written in accident, I have endeavoured to epitomise, or, rather, Lewis's system can be read, without any difficulty, 20 to give in my own language, the substance of methods or 30 years hence, when the subject will have quite es- employed by Mon. Foucault and others for figuring caped the memory-the characters representing the and testing specula independently of stellar observavowels are very simple, and their position is not of the tions. These plans were described by Dr. Draper, slightest consequence, so long as they are written in though not with all the details given below, in a book the same order, as in longhaud; the only awkward published in 1864, entitled "On the Construction of a character to join to others in this system is that repre- Silvered Glass Telescope, 154in. Diameter." senting ch; but another character can easily be substituted. Should "Hermit" wish to constantly write the same sentences-as, for instance, "Your last letter duly received," he can add a character representing the whole of such sentence without causing any confusion; any word may be written as spelled, or as sounded-that is, phonetically; any number of figures also are expressed in this system without taking the pen off the paper; quite as much time is occupied in making a dot, even, as in writing three or four words in shorthand, because there is no necessity after a little practice to lift the pen from the paper at the end of each word. I was able to write 60 words a-minute after a

more.

MAC D.

For a testing room he chose a long underground apartment, the apertures of which can be closed in order to be as free as possible from vibration and the disturbing effects due to variations of temperature.

For a support a piece of wood somewhat thicker than the mirror, and curved out to fit its periphery, is nailed to the wall about 3ft. from the ground; this is then lined with several thicknesses of blankes, so as to form a pad for the bottom part of the speculum to rest upon, the latter being prevented from falling forward by means of two wooden buttons near the top, which secure it, but so as not to bind it in any way.

Exactly opposite the speculum, and in its centre of

| curvature, is placed a'lamp giving a very strong ligh
the ordinary glass chimney is removed, and one of
or tin substituted, having opposite the very bright
part of the flame two holes drilled about the halfe
an inch or more asunder, the one being about 1-50th
and the other 1-300th of an inch, or less, in diameter.
The smallest hole is the one used in testing, the other
merely acting as a tinder; these holes must be drilled
in the same level, so that when the image of the larger
one is obtained, by turning the chimney round a little,
the smallest will come in view. Close beside the lamp
is placed an eyepiece, magnifying about 39 times.
through which the enlarged image of the hole is con-
veyed to the eye.

If now the speculum be of a perfectly spherical figure, the image of this hole will appear round and distinct, encompassed by diffraction rings. But if its surface be at all irregular the image will be found distorted, or having wings, or it will present some other equally anomalous appearance. The aperture of the speculum can now be stopped off in zones about an inch broad, when, should the form be regular, no alteration of the eye-piece will be necessary to preserve each separate zone in focus.

In judging of a parabolic figure, the longitudinal aberration of such a figure when reflecting rays proceeding from its centre of curvature must be calculated, and the form (or curvature) of the various zones altered by means of local polishers (small polishers varying from 1 to 8 deg. in diameter, made and worked in the usual manner either by hand or machine), until the necessary aberration is obtained. A second test used in conjunction with this one completes the operation of testing. In this test for the eyepiece is substituted an opaque screen, behind which the eye is placed, and the edge of the screen so moved as to shut off nearly all the rays proceeding from the mirror to form the focal image of the small lamp hole; and just when the last rays are departing, an intensely exaggerated view of the figure of the mirror, with all its imperfection in relief of light and shade, will be presented to the eye. But if perfectly spherical the mirror will present to the eye the appearance of an equally lighted plane.

So exceedingly severe is this test that the smallest ruffles or undulations due to the irregularities of hand polishing, but which cannot be detected even by star testing or the most powerful microscope, are made plainly visible.

If the speculum possesses a parabolic or hyperbolie figure, an undulation or gradual rise in the surface of the apparent plane will appear as a zone having its greatest elevation midway between the centre and circumferenceof the mirror. If the above directions are carefully followed they will be found to afforda valuable criterion to judge of the quality of a mirror. But it requires some amount of practice upon specula of known goodness to be able to figure with greas accuracy by it. In the last-named test it is very important to place the screen and the lamp both precisely in the focus of the mirror. This will easily be found by moving them a little to and fro until the shadow named below appears to advance all over the face of the mirror equally.

"The appearance that a trely spherical concare mirror presents is that, when the eye is brought inte such a position that it receives the whole pencil of reflected rays, and the opaque screen is gradually drawn across in front of the pupil, the brightness of the surface slowly diminishes, until just as the screen is cutting off the last relic of the cone of rays, the mirror presents a uniform greyish tint, followed by total darkness, and gives to the eye the sensation of a plane.

I will, if desired, describe Dr. Draper's and Mons. Foucault's system of grinding and parbolising. It is spoken very highly of, but will be found rather troublesome. It certainly gives good results on a large glass. It is superior to the method published by the Rev. H. C. Key, and lately so ably detailed by Mr. Purkiss. I do not practise it my self, as I consider my own plan much quicker, and capable of producing better figure, especially on a small glass. I shall probably recur to this interesting subject in future letters.

Next week I hope to have something to say in fa vour of the "Phantom" veloce, one of which I have just obtained, but owing to the accident named above

kave as yet been prevented from taking a "spin " upon it. A better or more thorough-going piece of workmanship throughout I never beheld. 1 like the appearance of the wheel and the way" the tires are affixed. It certainly looks capable of doing all that is reported of it. All my friends who have tried it speak highly in its praise.

EDMUND M. T. TYDEMAN, 10, High-st., Brighton, P.S.-Would "Sigma" oblige me with a description of "Calland's" battery, which I see is stated to involve only one-fourth the expense of a "Daniell's?"

FEED-WATER HEATER.

SIR,-I have read your correspondent's letter, signed "James Baskerville," and beg to thank him for the correction. I wrote my letter to you rather hurriedly. I should have said "within 10° of the heat of the

always over nine weeks. During both periods, the work performed by the engine and its general condition were the same. The arrangement sketched by your correspondent is no doubt equally effective as that described by myself; but I think the nuisance caused by the noise of condensation of the steam would be a disadvantage, as also the passing of hot water through the pumps.

LLAH.

COMMERCE AND TRADE-HIGH MARKETS-
WAGES-STRIKES, &c., &c.

London his meridian altitude will then be 3810, at St.

steam issuing from the exhaust." This difference I require these two amounts to make 90°. Thus, at
ascertained by placing a thermometer in the exhaust
pipe and in the heated feed water. Passing by the Petersburg 30°, at New Orleans 60°, and at Quito 900
touch of sarcasm in one portion of his letter as a wea-Again, owing to the pole of the earth always pointing
pon unworthy of a place in a correspondent's armoury; to the pole in the sky, it does, as it were, shift itsens
I do not claim an extraordinary saving in the use of and moving gradually in three months after, or June
this arrangement, as your correspondent seems to 20, the earth presents the same appearance as in Fig.
suggest; but I do say that my experience warrants
2. Then it will be summer in the northern hemi-
my expression when I say that this heater is a very sphere, and the days will continually increase in length
effective appliance. Against your correspondent's towards the north pole, and consequently the nights
figures I beg to place the fact that for two and a-half
diminish. If we count from S towards H, which is
years before 1 erected the beater described, my con- supposed to represent the horizon, or boundary of
sumption of rough slack was a boat-load every seven light and darkness, we shall find that at the equator.
weeks on an average, and for over 20 months after the
as before, the day is 12 hours long; but in proportion
heater was in operation, the same boat-load served
as any place is distant from that line, so its days
increase in length until we come to 2340 of the north
pole, or to the boundary of the Frigid Zone. Here we
shall find, by counting the meridians, that the half day
is 12 hours that is, that the length of the entire day
is 24 hours, as, for instance, in the northern part of
Sweden. His meridian altitude will there be 47°,
because 234, the declination of the sun, added to 23.
the complement of the latitude, will make that
amount. He will then have reached the point where
he begins to recede, and at noonday will be vertical to
those who dwell under the Tropic of Cancer, and will
continue to be so for several days; for it is here that
"Sol stat," or is apparently stationary for a short
time. By reversing the figure, it will present the
appearance of the earth at the winter solstice, when
the south pole is turned towards the sun, and the
north pole away from it; and the consequence is, that
the days continually increase in length in the
southern hemisphere, the sun becoming daily
higher and higher in the one, and lower and lower in
the other, until he has reached his greatest south
declination, when his altitude at London will be the
complement of the latitude minus the declination, or
Thus we find that, having only a
38-23 = 15o.
small are to pass through in the enlightened hemi-
sphere, his long delay in rising is accounted for by his
having a longer tour to take; and when he makes his
appearance, it will be as much to the south of the east
as during the summer it was to the north of the east.
He will then be vertical at noonday to those living
under the Tropic of Capricorn, and the reason will be
apparent why our antæci have summer when we have
winter, and why their day is exactly equal to our
night. If, then, we wish to see the position of the
earth with regard to the sun at the summer solstice,
we must elevate the north pole 23 above the wooden
horizon. But to show its position at the winter sol-
stice, the south pole must be elevated the same number
of degrees, when, by turning the globe on its axis, it
will be seen that the north pole has entirely lost sight
of our golden luminary.

I

SIR,-Having read the very instructive letters of Sigma' and others on Commerce and Trade,' I would like to see the subject sifted from the very bottom. have been a subscriber from the first, and I think the above subject is as important as any. Not many weeks ago the Glasgow joiners were out on strike for the nine hours a day movement, and they have gained, Now, in all future contracts the prices will be higher; then, of course, house proprietors must raise their rents. Now, all other trades, seeing the success of the joiners, will in time try to follow. Now. I would like to have the opinion of some of my fellow-subscribers if 8, or even 9 hours a day, would pay, were it to become the general law?

I have been thinking about the Land question (but not Irish land). My opinion is, if Government were to buy up the whole of the Three Kingdoms, and sublet it in portions to the highest bidders, then the money would return to the national purse, it would reduce taxation, and strike at the root of all discon

tent.

WILLIAM JARDINE, Risk-street, Dumbarton.

READINGS FROM THE GLOBES.-No. IV. (Continued from page 278)

SIR,-It must have occurred to every one, when viewing the sun, what a different appearance he presents at different seasons of the year, sometimes reaching a considerable altitude in the heavens, and at other times being low, and making but a small tour in his daily course. Even an uneducated person cannot but be struck with this property of the sun; but travellers who have visited the torrid and frigid zones must have beheld with still more curious feelings the appearanees which he presents in these parts-in the former becoming vertical, and in the latter never setting for days, and even months together. Early observers of the heavens noticed that he did not rise daily in the same point of the compass, but that half of the year he rose more and more northward, and became higher and higher until he had reached his maximum height, and then began to recede, and for another six months of the year to rise more and more southward, and become still lower and lower, and by logical déductions they have been able to form an intelligible theory of the sky, so that anyone can, without much effort, understand

"Quid tantum Oceano properent se tingere Soles Hiberni, vel quæ tardis mora noctibus obstet." "Why winter's suns to ocean haste away,

Or what obstructs the nights to make them stay." It will be our object to show how these different appearances may be readily explained by the globe, and we will begin from the point Aries, when the sun makes a fresh start to pursue his accustomed round. When at this point he is crossing the equinoctial line, and the days and nights are then equal, or 12 hours long, in all latitudes as far as the poles. To represent this by the globes we must place its two poles in the horizon, as It appears in Fig. 1. It will then appear by an inspection of the figure how it is that the days and nights are then equal all over the world; for, let S. E. represent the equator, N. P. the north pole, and S. P. the south pole, round which the world spins. The meridian lines are imaginary lines, contrived by geographers for the purpose of giving a better idea of the revolution of the earth on its axis. In this situation, then, if we count from 8 towards either pole, we shall find six spaces, each 16° in width, which is equal to half the length of the day in all latitudes. The days will therefore be 12 hours long, and the nights 12 hours long. As the sun is supposed to be in the point Aries, he will be vertical successively to all living at the equator, as they pass under S. At the north and

T. S. H.

THE LATHE AND ITS USES.
SIR,-I quite agree with another subscriber of
"ours,
of this week, respecting patterns for lathe,
and have no doubt that, notwithstanding all that has
been published, good working drawings to scale, of
the most recent pattern, and containing all the
improvements that an amateur would be likely to
want in a lathe, would be highly prized. It is not
enough to see a finished engraving, without the various
parts shown in section, &c., and some guide as to rela-
tive sizes. There is no journal that can do this better
than "ours," even if so well.
out 100 guineas, nor is there any need of one costing a
We don't want to lay
large sum. I would suggest it should have fret saw
and vertical drilling apparatus to fit, and work on it,
as well as many other appliances that brother ama-
teurs could give "notions" of.

J. F.

DARK LINES IN SOLAR SPECTRUM.
TWILIGHT.

sected angles would be a curve of the third order, and not a circle. Moreover the method would be rather troublesome in practice.

It led me to investigate the curve which has the property of trisecting all angles drawn from two given points in the manner of the method referred to, and which is, in fact, the place of the apex of all triangles standing on a given base, and having one of the angles at the base three times the other.

The equation to the curve when referred to rectangular co-ordinates is cubic, and has not an encouraging aspect.

Its polar equation is simpler

SIR,-I have read, noticed, and examined, with much interest, the thousand-and-one proposals, suggestions, and drawings, made in your paper, respecting the best and easiest mode of self propulsion. Your correspondents' various machines, seem, according to their own acconnt, to go at all speeds, vary. All the proposed ing from 6 to 30 miles an hour. machines would no doubt fulfil the expectations of their inventors, if a journey of 50 miles each way was all down hill, both there and back, but, unfortunately, in a journey both ways, there is just as much up hill as down hill to go. I have never yet been on one of these manumotive engines, but I have seen many of them in the street and on the highways; they all go first-rate down hill, but up hill, or even on a level road, it appears to me to be fatiguing work, and I have come to the conclusion that the whole stock of other pedes and cycles, are up to nothing, when put velocipedes, pedespedes, tricycles, bicycles, and all really to practical work, and particularly in a hilly district. It is useless, then, wasting so much of your valuable space every week in describing these articles. The long and short of it is, we want, and must have, something really useful, practical, and powerful. A steam carriage is what we want, but at present steam carriages are practically useless in consequence of the very many vexatious restrictions placed upon their use by a house full of M.P.'s interested in railways. It is our duty as English mechanics, to agitate for the repeal of these restrictions, and for the abolition of all toll bars, and never rest satisfied until we have accomplished our object. When such eminent men as Sir Joseph Whitworth are in favour of road locomotion, I think the matter is at least worthy of discussion' in your pages. My object in troubling you, is to induce some of your clever contributors to take up the matter in earnest. I think, as mechanics, we ought to take a deep interest in anything that will increase and benefit the iron trade. I am sure I would make every effort to own a steam carriage, were their free use permitted, and I look forward with pleasure to the time when I shall be able to take out my steam carriage, and give my wife and children a pleasant ride into the country, when my day's labour is o'er, or when I can reside a few miles from town, and go to my work in my own carriage. This proposal may seem ridiculous on paper, but we have it within our grasp if we will only go heart and soul into the matter. Then, again, look at the immense benefit it TO TRISECT AN ANGLE. would confer on tradesmen of all classes, builders for SIR,-In your impression of the week before last instance, who may have twenty men working at a job, there was an ingenious attempt at the solution of the three or four miles from their shop. These twenty men well-known problem to trisect an angle. The method, each lose one hour of their master's time every mornhowever, was only approximate as the locus of the tri-ing morning going to the job. Now with a steam

SIR, I wish "Steersman (3991) had not required my opinion upon the spectra of the fixed stars, as I would much prefer allowing the spectroscopist to correct his own errors.

There is no doubt the spectra of comets and nebulæ reveal the character of these objects; but as to remote suns, diminished by distance to a point, what can be expected from the spectroscope but evidence of the power their light still possesses of effecting chemical change in our atmosphere?

With reference to the presence of iron in the air, where does "Steersman," imagine the surface matter of the globe comes from? Space is not an empty void.

T. A.

P.S.-I hope Mr. Proctor will pardon my obtuseness but I cannot understand him. There is no such thing in nature as a crepuscular curve; for refraction is not concerned in the phenomenon of twilight.

carriage, they would go in fifteen minutes, which would be a clear saving of fifteen hours per day to the master. Certainly the coal and the driver's time would cost something, but that would be amply compensated for by the men being fresh and ready for work, instead of being fatigued by a four miles journey. Then, again, very few small tradesmen can afford to keep horses, because they are always eating, whether they are working or not; now a steam carriage would only be consuming when it was working, the consequence would be, every one who could spare the money, would have his own private carriage; this would give a great impetus to the engine trade, and find employment for thousands of our intelligent mechanics, who are being driven out of their native land to seek that employment which is depied them at home. Any objections that our M.P.'s could make or raise, could easily be met, and the public safety secured by using proper precautions, such as limiting the speed of the engine to, say eight miles an hour in towns, and fifteen miles an hour in the country, and by compelling the owner of each carriage to place a speed indicator, and also a water and steam indicator to his boiler, in such positions. that they could be seen distinctly by both himself and the general public outside, who could complain if he violated the law, so as to endanger the public safety. Then again, each carriage should carry a pair of lamps. Coke should be the fuel to be used, so that no black smoke would be emitted; in fact, only let the want of a compact and useful article be felt, and the inventor will step in and supply the want. It would scarcely be advisable to allow lads under, say 18 years of age, to be in charge of them. In conclusion, let me urge your readers to consider the importance of this proposal, and never rest satisfied until we have gained our object. Mr. Allen and his 33,000 brethren of the Amalgamated Engineers, will, I am sure, come to the rescue. The question only wants agitating, and I know of no paper so suitable as the ENGLISH MECHANIC so take the lead in the matter. What a boon it would confer upon commercial travellers with their tons of luggage, to be able to go through the country districts, where there are no railways! It would be to them an immense saving. May I ask you, Mr. Editor, to append the present Act of Parliament on the Use of Steam Carriages, for the benefit of your numerous readers?

A PATTERN MAKER. ["A Pattern Maker" makes some suggestions on steam carriages well worthy of attention, but why condemn "the whole stock of velocipedes," if he has "never been on one of them." He wants a steam carriage "to give his children a pleasant ride into the country," but every one has not a wife and children to take. Possibly at one time there was too much of our space occupied by notions and fads in connection with velocipedes; but for some time past we have only given insertion to practical suggestions and realised facts, and certainly "A Pattern Maker" cannot reasonably object to space being so occupied. -ED. E. M.]

A FOUR-WHEELED VELOCE. SIR,-I see that you give in your publication considerable attention to velocipede construction. It is an interest subject, and deserving of the space you devote to it. The bicycle seems at present perfected in the "Phantom "veloce, and for all who can ride on a two-wheeled machine there seems to be nothing more to be desired. But there is a large class of people, both young and advanced in years, especially the latter, desirous to make use of this kind of locomotion who cannot or will not adventure them.selves on two wheels. I have been thinking that for them there might be a safe and easy-going machine constructed which would be light and swift, too, if two bicycles could be mechanically connected so as to make one machine with four wheels, on which two persons could ride abreast. This would be a safe and social way of riding the veloce for the class of people referred to, if our mechanics should pronounce it practicable. The tricycle does not answer the purpose, and is therefore but little patronised. It is possible that you have received suggestions of this kind already, and that they have been satisfactorily disposed of; if so, you will please excuse this communication as in reference to your useful publication I am but

A NEW READER.

nisation of a superior character could be carried out
with very successful results. What is to prevent us
at a time when this great question of emigration is
forcing itself upon every thoughtful mind, to set to
work and form the nucleus of a new and prosperous
colony, to be established in some favoured spot of our
glorious dependencies, which may, in the course of
years, become the happy home of thousands of our
surplus population? I can see no reason why this
scheme could not be easily carried out by the aid of
your liberal pages, and of the able and willing minds
which so freely contribute to their contents. Not
only so. I believe that a colony formed with such
materials as would thus be collected, would be initi-
ated with the advantages of a greater diversity of
means, talent, and a more general diffusion of useful
intelligence than in almost any previous instance of
the kind, thus making a start with all the valuable
elements of civilisation at the very outset. I believe
now that the attention of Government has been
urgently drawn to the subject, terms of a most
advantageous character could be made in the way of
a grant of land, and other important concessions.
If you think, Mr. Editor, that my views are correct
on these points, and you think proper to submit them
to your readers, with the view of carrying them into
practice, I will be glad to correspond with any gentle-
man competent and willing to become members of a
provisional directorate in such a movement, with the
view of an interchange of opinion on the subject,
after which a permanent directory could be esta
blished, in at least one principal seaport in England
and another in Scotland, and another in Ireland;
and after certain essential arrangements have been
made, measures would be taken to make the move-
ment public through the pages of the ENGLISH
MECHANIC and other media, with the view of receiv-
ing applications for membership, which I trust would
reach 1000 at least in a short time. Such a number
of colonists, with its combined capital, could, by
chartering vessels on its own account, transport
itself to the required destination at a very moderate
cost, and by the employment of its supposed superior
intelligence in the selection of machinery and other
appliances, agricultural or otherwise, of the most
approved description, it would no doubt succeed in
establishing itself with as small a share of discomfort
as is possible under similar circumstances.

ALEXANDRA.

[The above letter is written by a strong-handed

and clear-headed, Seotchman. It may contain the
germ of an historical movement; at all events, it
has our hearty approval.-ED. E. M.]

COTTON SPINNING.

SIR, I promised in my last letter to speak further on the subject of drawing boxes; with your permission I will now do so. But first let me say a word or two about the filaments that drawing rollers have to disentangle and draw out. Peradventure, there may be some lads, and even "big 'uns" too, who are not fully aware of the fact that cotton fibres are long tubes, more or less tortuous, and individually of no appreciable strength. That they somewhat resemble the hair of animals, and grow upon the surface of the cotton seeds much in the same manner as hair grows upon the head. Different classes of cotton have different, and to the spinner, very important characteristics-as the average dia Leter of the fibres of upland" cotton = part of an inch, of Sea-Island

1

2009

1

6000

1

-

1

extraneous matter from the cotton.

then, that the medium betwixt these two extremes is
the condition that will be most effective in rendering
"good work," It may not be amiss, although the
thing is self-evident, to say that long twisted fibres
offer the greatest resistance in drawing, and short
straight ones the least. Another very important con-
sideration in this matter is the speed at which the fibres
are drawn out; for it must be remembered that the
rollers do not give to the fi'aments a gradually increas-
ing rate of motion from one speed of travelling to
another, but draw them out by a sudden jerk, so that
the strain upon the fibres caused by a long draught,
may be considered as equal to that of a short draaght
at a correspondingly quick speed. (Let me here refer
the lads to the Rev. E. Kernan's "Science for the
Young," in this vol,, Inertia, page 105). Before I re-
sume the subject, let me remark that this latter com-
mon sense fact plainly demonstrates that no very quick
speed of rollers can ever be attained with long draughts,
though it is not the speed itself that is mischievous, but
the abruptness with which the fibres are jerked from
one degree of motion to another. There are but few
spinners of any experience who do not know that a
very triding increase of speed often makes the "work"
unmanageable. Many things may contribute to this
result, but the chief one is the too abrupt jerking of
the films between the rollers; and a shorter draught
put in operation with the increased speed would be a
remedy for the main evil. Now, the cylinder" of a
carding engine travels at a much quicker rate than the
doffer" that "strips" it of the carded filaments
consequently, the filaments cannot be laid upon the
surface of the doffer" longitudinally and parallel,
but in a confused mass. In this state they are combed
from the "doffer" by the " doffing comb," and trade
to pass in a continuous web through a funnel-shaped
nozzle; and by this means are contracted from the
broad web to the form of a flimsy rope.
This flimsy
rope of fibres has to be drawn out by being passed
through various speeds of rollers until its tenuity
equals the intended "counts." (The "counts"
the number of hanks there are in a pound weight of
the material-810 yards = 1 hank). The "drawing
box" rollers have, of necessity, the greatest speed
given to them, then, after taking into consideration
the above facts, and remembering, moreover, that be-
tween the first pair of rollers there are often upwards
of 40,000,000 of fibres passing through at once, is it at
all surprising that the question asked by "Factory
Lad" should receive so many different answers. How-
ever," Factory Lad," page 231, says, "I find Mutual
tically found to be the best arrangement working fair
Improvement' comes the nearest to what I have prac-
Dholiera -I have my draughts-

are

341 × 175 × 1·17 = 7·06." Now, if" Factory Lad" is not "running" at a great speed, nis arrangement may do.

(But 3:41 x 175 x 117 6981975, not 7:06.) However, it is incomprehensible to me how "Factory Lad's" Surat fibres after being "coaxed" (vide "H, C. S.," page 183) from 1 to 2, should be thereby prepared for being jerked from 2 to 7. "Mutual Inprovement," page 230, says he must give me "credit for knowing better than equalising the three draughts." I am afraid I do not deserve the credit; for, seriously, I do believe the arrangement he advises, in these days of "keen" competition, with its concomitaut, quick speed of productions, would be all the better for some amount of equalisation. If, however, he thinks differently, I shall not quarrel with bin. In a former letter, I said it is a "pennywise and pound foolish" thing to have a draw-box attached to the carding engine for the purpose of adding a considerable amount to the draught of he engine. "Mutual Improvement" says heet understand why such is the fact. He further it is stated that some of our most successful spin.. ers work them, and asks if I will give my reasons for condemning them. To be sure will, M. I.," lad; at the same time, let me say, I do not want any deference to be given to my opinions, but I would rather that we should all bear in mind the fact, that we may all look at any subject from a necessity for us to "pitch into each other." However, different point of view; so that there is not the least simultaneous with the process of drawing, it is found to be necessary and profitable to put in operation the "doubling" process, in order that the inequalities of the "work" may counteract each other. And, furthermore, in order that as the filaments are drawn out longitudinally and laid parallel to each other, their ends may be properly arranged, one a little advance of the other; in the same order as a builder lays the courses of his bricks, that the joints may be well overlapped. Without this condition, it is impossible to make a good thread; and so fully is this fact recognised that the doubling process is carried out by some manufacturers to the extent of from 80 to 100,000 times. It is a self-evident fact, that as the draught raultiplies the length of the yarn or sliver, it also multiplies its defects, unless it is prevented from so doing by doubling. Short draughts and plenty of doubling will produce good, even yarn, that will bear the strain of quick speed-sour bulwark against competition. "M. I." may now see why I con demn drawboxes attached to carding engines for the purpose of adding a considerable amount to their draught I am somewhat puzzled in my attempts to find out by what "preparation "Harmonious Cotton Spinner" has resolved the major chord of his 1st letter into the minor chord of his 3rd. How does he make his 3rd harmonise with the tenor of the ENGLISH MECHANIC?

of Surat, from to The process through 500 2000 which the cotton goes after it is "picked from the seed pods, and previous to its being compressed and packed up for exportation, is a mechanical scutching, for the purpose of tearing off the fibres from the surface of the seed-coat to which they obstinately adhere; and for the further purpose of expelling other How far this process has hitherto been successful, those can tell, to their cost, who have paid from two shillings to two shillings and sixpence per pound for sand, seeds, dust, stones, bricks, &c. However, anyone at all acquainted with cotton spinning knows how utterly impossible it is to tear off the fibres from some portions of the seeds by any amount of scutching, short of one that will be disastrous to their spinning qualities after the cotton has been compressed and felted together, and, especially, is this so with the chief classes from India? When portions of the most common descriptions of cotton come to be examined after being" willowed," "scutched," and "carded," they will be found to consist, not of a mass of single fibres commingled together, but in the mass will be found numberless minute "motes," with a small cluster of fibres adhering to them. The object of the carding process is to eliminate the filaments individually by a combining action, but so tenaciously do these minute clusters adhere together that even the "teeth" of the cards will not separate them without such an arrangement of them as would break the rest of the fibres to pieces. Here let me observe that these minute motes affect the drawing qualities of the cotton very materially; no cotton in which they exist will draw out equally or evenly, but in small patches or clusters which ultimately produce a knotty, uneven thread; because, behind each knot or cluster of fibres there must obviously be a corresponding "thin place," which gives to the yarn the appearance of having been To give advice is an easy matter, partially cut through. The strength of these thin generally sponking, and most people have lots of it points, be it observed, is the strength of the yarn. Ito spare-but to give information is a different must further remark that the length of the fibres and thing! the degree of their natural torsion also affect their drawing qualities, inasmuch as they affect, to a great extent, the amount of force with which they resist the quickened motion of the front pair of rollers, or, in other words, inasmuch as they affect the amount of force with which the latter or bind portion of the fibres resist the quickened speed of the frout portion. Now it is obvious enough that the amount of this resis Having noticed some anxious inquiries, from time tance or holding-back force must also depend upon the to time, on the part or individuals desirous of emi-distance there is betwixt the rollers. If this resistance grating, it has struck me forcibly, that through the be too great, the fibres will be broken; if too little, they agency of your trustworthy journal, a scheme of colo- will draw out in clouds, or irregularly. It follows

AN ENGLISH MECHANIC COLONY. SIR-I beg to add my testimony to the very able manner in which our MECHANIC is conducted, and the great success it has attained. This is the result of your wise policy of encouraging all your readers to become also contributors. "In the multitude of councillors there is wisdom." Curiously enough, I have known instances, long before the advent of your journal, of similar periodicals starting off with great eclat and success, mainly owing to the primary encouragetnent of this same feature, but somehow, as soon as the precocious gentleman thought himself safely out of his leading strings, the communications and queries of the life-giving amateurs were pushed from corner to corner, and ultimately to the cover of his precious pages, the effect of which, upon their intrinsic value and on the subscription list, it is needless to describe. It is clear, a journal like yours may be made useful in a thousand ways to its subscribers, which must soon become legion, whatever may be their individual position in society. We can easily gather from its pages, that it represents to a large extent, every grade of education and intelligence, from the inspired philosopher to the humblest mechanic or agriculturist, all ready to yield up the benefit of their special experience to their fellow subscribers. Under these circumstances, it is difficult to conceive almost any object, however important, or however comprehensive in its character, in connection with which your journal could not be of most vital service.

E. SLATER, Burnley.

ORGAN PIPES-CLOCK BELL. SIR,-Having been benefited by the communications of others, I feel bound to give any useful result which I seem myself to have attained. I have taken "Adept's" plan of open wood pipe with the bevelled mouth-piece turned to the inside. But instead of the short sharp bevel I have made a lengthened easy slope, extending about two-thirds up the pipe. have also bevelled the back to correspond, reducing

the wood where it meets the block to the thinness of Several palm trees yield also a kind of wax-the
pasteboard. The space thus gained in the interior I Carnauba, the Humboldt palm, &c., but I intend only to
have economised on the outside, making the pipes of mention here the fat or oil-yielding plants. Another
less depth, the smaller pipes by one-eighth to three-time, perhaps, I might give a list of the vegetable
sixteenths of an inch, and in the middle of the organ
by as much as a quarter inch. I find the pipes so
treated speak readily, with a clear and pure tove. I
think the plan will be appreciated by all who know the
value of space on an organ board both for placing pipes
and giving them room to speak.

Grape seed oil (Vitis vinefera). Lombardy, &c. ; 18 deg.; English and French measures, so that when they get for burning and soapmaking.

12.-CORNEL ORDER, OR CORNE.E.
Cornel oil (Cornus mus). Europe.

13.-NUTMEG (RDER, OR MYRISTICACEÆ.
Yayamadou ouarichi (Virzola sibefera). Abundant in
Guiana; deserves attention for candle making.
Combo, Gaboon (Myristica angloensis), 72 per cent.
medicinally, and for fabrication of candles.
Bicuiba, ucu-uba, Brazil (Myristica bncuhiba), used
Rarab, Mayotte (Myristica sp.)

Nutmeg butter (Myristica moschata), Moluccas.
Poondy seed (Myristica malabarica)."
4.-CUSTARD APPLE ORDER, OR ANONACE.E.
Monodra Grandiflora, Gaboon.

15.-POPPY ORDER, OR PAPAVERACE.E.
Poppy oil, Eilette oil of the French (Papaver somni-
ferion). Cultivated in France; seeds also exported
from India; 48 per cent. Two sorts of oils, white and
fabric, used for eating, burning, and painting; second
sort for soap making,

Prickly poppy, yellow thistle; Sheâl Katta, Bengal (Argemone mexicana), East Indies and America.

16.-CRUCIFER ORDER, OR CRUCIFEREÆ.

Colza oil, rape oil, from Summer Colza (Brassica campestris), 23 per cent., and winter do. (B. napus) 31 per cent. Plant cultivated in Europe, principally in Belgium; seeds also imported from the Black Sea, the Baltie, East India, &c. The oil is used for lubricating machinery, and, after being refined, for turning in lamps. Trade somewhat impaired since the introduction of petroleum.

Ravison seed, from the Black Sea, is a wild sort of celza, often mixed and dusty, yet yielding a good percentage of oil.

a drawing with millemetres attached
they could
translate it into English, he would confer a lasting
benefit on all practical mechanics, and especially on
a brother

SIR, With reference to "Aqua's" query, Griffin's solutions contain equivalents in grains, in a decigallon. As they are addressed to Mr. Davis, who will attend to them, I shall not answer the rest. Has "F.R.A.S." personally had any experience with bisulphide or amylene prisms for the spectroscope? For many purposes I prefer them to flint glass, With an inch and a quarter spectroscope, I find a train of five are all that can be wanted for chemical purposes. URBAN.

SIR. The favourable notice that appeared a few weeks ago in the ENGLISH MECHANIC of Mr. Dyer's book of replies to Parallax" led me to read that book, and to make a number of computations, with a view to give some delinite numerical expression to instance, referred to by him in his introduction) find those errors which many people (Mr. Dyer's friend for it difficult either to admit as true, or to prove false Perhaps a few of the results may prove interesting to many readers, without exciting or fostering a spirit of controversy. I submit the following by way of example:

1. Given A B = 69.091 miles x degrees in S. Let SAB be a right angle, and the triangle be a plane

one.

12. How are the P D's found? 13. What must be done with all other lines (horizontal) at angles other than 90 and 45°? 14. What accompanies every vanishing at 90° to the P P, and how are measuring points point? 15. What are the measuring points for lines found?

The following is a list of abbreviations common in perspective:-V, centre of vision; D P, distance MP, measuring point; HL, horizon line; GL, ground points; S P, station point; V P, vanishing point; line; PP, picture plane; GP, ground plane; OP. original plane; Vg P, vanishing plane; PL, picture It will be well for the student to get master of the theory, and begin with a little practice. few foregoing hints, and next time we will leave the J. W. BEDFORD.