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tool carriage F by hand to
anv point of the width or
depth of the machine,
whilst, by raising the
handle, he also deter-
mines at will the movement
of the lower carriage D,
and causes it to act succes-
sively by means of the ratchet
cylinder E and screwed rods
b, on every point lengthwise
of the machine. Thus the
attendant operative can not
only move the tool or
hammer m instantly to any
possible point of the mill-
stone A, and cause it to
attack the surface with any
force or to any depth re-
quired, but he can also had
the tool fixed upon one
particular point as long as
he thinks fit. When the
carriage D is at the end of
its course it is taken back to
the starting point by means
of a crank, which acts
directly upon the ratchet
cylinder E. The wheels
then slide upon the screw
b, which remain fixed. To
keep the driving-strap or
band on the pulley u at its
necessary tension, whatever
may be the position of the
carriage D on the frame B,
an elastic cord or band
must be used for that pur-
pose. The sand or dust pro-
duced during the work on
that part of the stone under
operation is constantly ex-
pelled by a small bellows
2, actuated by each upward
movement of the tool carrier
k."

We have in this machine
a horizontal rectilinear sli-
ding movement, which
causes the cracking to be
done in straight lines, and a
screw-feed motion at right
angles thereto, by which
those lines are made at
regular distances apart. Any
arrangement for securing
the truth and level of
the stone is, however, wholly absent; the frame,
resting on the stone, covers too small a surface,
and the inner corner of it being over the central
part of the stone, which is always somewhat de-
pressed below the outer part, must be held up
by a special support, the adjustment of which
would always be uncertain; otherwise the frame
would rock on the two corners which rest on the
outer part of the stone.

(To be continued.)

SET."

face of the stone upon which it is intended to
operate. The tool carrier k is connected by a
joint to a lever n, actuated by the cam, the
abrupt projections of which give an increased
action to the hammer. This lever n is thrust
away from the said cam by a spring o fixed to
the carriage F in such a manner that contact
only takes place in proportion as the spring is
compressed by the pressure of the lever . The
action of this mechanism is rendered more sen-
sitive by the combination of several spring
levers all controlled by the same handle h. It
will hence be perceived that the more the lever
h is pressed down the more action the cam g has SOLOMONS' NEW PATENT "COMPOUND
on the lever n, the ascent and descent of which
is communicated exactly to the hammer, and in
this case the latter acts on the stone to a corre- IN
N 1868 Dr. Allnatt wrote to the editor of the
spondingly greater depth, the reverse of which Times suggesting the great advantage that
will evidently take place if the lever h is moved would accrue to meteorological observers from
in the reverse direction. When this lever is the possession of a complete set of instruments.
raised it comes in contact with a lever p, the
extremity of which works in a fork r, and acts He, however, lamented that the cost of the com-
against a screws, which can be raised or lowered plete set-consisting of barometer, thermometer,
to any desired degree to limit the ascent of the hygrometer, rain gauge, anemometer, and zone
said lever p. To this latter is joined a vertical cage, when constructed with tolerable accuracy,
rod carrying a ratchet or catch t, which gears
into the grooves or teeth of the ratchet cylinder
E. In this manner the greater the ascent of the
lever p the further the catch t will cause the
cylinder E to rotate, and the more the carriage
D will be displaced on the screw rod b.

prevented the majority of observers from obtain-
ing them. He suggested the construction of a
combined set of all the required instruments
(except of course the rain-gauge), mounted on a
solid mahogany frame, which should exhibit at a
"It now remains to explain the driving gear
and the transmission of movement to the various glance all the existing physical elemental condi-
parts of the machine. The pulley u, mounted tions. The Messrs. Solomons, of 39, Albemarle-
on the vertical fly-wheel shaft G, receives motion street, Piccadilly, speedily responded to Dr.
directly from the driving power; this shaft com- Allnatt's suggestion by the construction of het
municates movement by the aid of a pair of compound set herewith illustrated, and which het
bevel wheels to the horizontal shaft H, the end Doctor in a second letter to the Times charac-
of which carries a grooved pulley round which terised as "indeed a multum in parvo." The set
passes a cord, passing also round a similar is indeed the best and cheapest we know of, its
pulley on the shaft f, carrying the cam g, which
actuates the double bevelled hammer or tool m,
as above described. The workman directs the

price, £2 12s. 6d., being so low as almost to in-
spire distrust. Its accuracy, however, is guaran-
teed by the testimonials of numerous purchasers

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[graphic]

who have hastened to avail themselves of an
opportunity hitherto afforded by no other me-
teorological instrument maker.

The set consists of a barometer, with double
vernier, maximum and minimum thermometer,
Mason's hygrometer, thermometer with centi-
grade and Fahrenheit's scales, and storm-glass
The tubes, enamelled, are of best quality; the
scales, of stout polished boxwood firmly screwed
to a solid walnut, oak, or mahogany board, mea-
suring 3ft. 3in. long, by 8in. wide.

Messrs. Solomons recommend the addition of

their patent vernier thermometer, which, at the
slight extra cost of 12s. 6d., renders the set
complete.

The scales and two verniers of the barometer

are engine divided, and allowance is made for capacity and capillarity; so that it approximates in accuracy the nearest to the Kew standard. The storm or camphor glass, though much consulted by the late Admiral Fitzroy, is probably of little real use. Still it is attended with great interest, and being made by Messrs. Solomons exactly in accordance with the Admiral's receipe and with the glass tube of a larger size than usually sold is rendered, which prevents in a great degree the attraction of the crystals to the sides, it is rendered as useful as possible. The hygrometer is a most important part of the set. Its aid to the physician is invaluable in the regulation of the degree of moisture or dryness necessary in the air breathed by his patients; to the householder who wishes to keep the air of his rooms in its proper condition; and to the horti

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culturist whom it enables to determine at will the climate of his conservatory. We think Messrs. Solomons fairly entitled to the credit of having, produced the best and cheapest set of meteorological instruments yet ntroduced.

THE PROPOSED DARIEN CANAL. Darien appears to be THE Isthmus

Tregarded by the majority Pamerican

scientific opinion as the most suitable site for the

roposed inter-oceanglishman, claims to have made the most complete reconnoissance of the Isthmus of Darien. He claims to have found a

practicable route, with an elevation of not over 190 feet, and he thinks even less may be found. We submit his map.

It will be seen from the map that he has a canal of 21 miles, and deepens the Sucubti 12 miles, then navigates the deep streams, Lara,

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LARA

CANAL

SAVANA

GULF
OF
SAN MIGUEL

BRAYAI

R

100 yards wide at top and 26ft. deep. With
its present imperfection they have taken nearly
100,000 dols. of tolls. The Darien Canal, costing,
say, 75,000,000 dols., would at least pay 10 per
cent. profit, and Dr. Callen estimates the actual
saving to the commerce of the world in 1857
would have been 48,130,208 dols.-nearly enough
to have built it.

THE GERM THEORY OF DISEASE.

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I quite agree with Dr. Bastian that there is no proof that the organic matter of London air is I do not believe it to be all germinal matter. such. In fact, I have twice or thrice written down what the researches of others make the floating matter of London air to be, but tenderness for the public has withheld the description from the press. In the lecture, a report of which you did me the honour to publish, it is stated that "there is no respite from this contact with dirt, and the wonder is, not that we should from time to time suffer from its presence, but that so small a porNa letter to the Times, Dr. Tyndall combats, tion of it would appear to deadly to man.' It " that I as follows, some of the arguments against is with reference, this bed by to m described the germ theory of disease. The really his germ theory of disease :— Amid the morass of wordy discussion and important point here is that the germs which are contradictory argument in which the germ theory mixed up with the floating matter disappear when of disease and the question of spontaneous gene- it disappears. Permit me to place in a connected ration are entangled, the fact and inference form before the readers of the Times the "indirect brought forward by Professor Lister regarding the evidence" on which, to the surprise of Dr. Basputrefaction of ounds appeared to me to pre- tian, I rely. Schroeder and Pasteur have demonsent a spot of perfectly firm ground. They by strated that air filtered through cotton wool is deno means involved the deprived wholly or in part of its power to produce monstration of the germ animalcular life. Why? Experiment with a theory of disease in all beam of light answers the question; for while it its generality, and I thought proves our ordinary air to be charged with that even those who are floating matter, the beam pronounces air which most hostile to the theory air which has been carefully filtered through cotton in its wider claims and bear-wool to be visibly pure. There are no germs afloat ings would be willing to in it; hence its impotence as a generator of life. concede that the origin of Again, Pasteur prepared 21 flasks, each containputrefaction, at least, was ing a decoction of yeast, which he boiled, in order placed beyond dispute. Dr. to destroy whatever germs it might contain. Bastian's letter in the Times While the space above the liquid was filled with of last Wednesday causes me to fear that this admis- Pure steam he sealed the necks of his flasks with a blow-pipe. He opened ten of them in the damp sion on the part of those still caves of the Paris Observatory, and 11 of whom he represents is stil them in the courtyard of the same establishdistant, and that it was a ment. Of the former only one showed signs of delusion on my part to hope life subsequently. In nine out of the ten flasks no organisms of any kind were developed. In all the others organisms speedily appeared. Pasteur ascribed this unexpected result to the subsidence of the germs in the motionless air of the caves. Is his surmise correct?

GOOD

ANCHORAGE

TUYARA R

PROFILE,

LARA

that it was near.

A similar delusion may cleave to my judgment when I say that in a letter which fills nearly a whole column of the Times, Dr. Bastian has not, so far as I can see, brought forward anything beyond an opinion affecting, in one way or the other, the position of Frofessor Lister. He deprecates "indirect evidence," aud speaks of the ambiguous experiments of Pasteur; he refers to the virtues of turnip infusions and to the killing of germs by heat; he expresses amazement, and protests against Laxity; he exhorts, he warns, he promises results "which will go very far towards the settlement of the much-vexed question as to the possibility of spontaneous generation." But he successfully avoids offering the shadow of an Savana, and Tuyara, 14 miles more, in all 47, j argument calculated to influence either affirmawith one or two tidal locks-no other. He tively or negatively the distinct issue raised in estimates this to cost about 34,000,000 dols., but my letter of Thursday week. his estimates are only for a canal 24ft. deep and 150ft. wide through the mountain or deep cuttings. It would be folly to dig such a small canal at the present day. The harbours at each end will accommodate ships of the largest class now known, and at low tide the depth of water at the mouth of the Lara is 50ft. The tide rises there 12 to 14ft.

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Will Dr. Bastian
forgive me for expressing the opinion that irrele-
vant writing has done, and is likely to do, more
damage to the cause of exact medicine than the
distinct statement of even erroneous views?
the one case we have a definite error on which to
place the iron heel of logic or of fact; in the other
we are met by a phantom which eludes both.
The question raised by my letter lies in a nutshell.
Either Dr. Bastian denies the inability of lung
filtered air to produce putrefaction, or he admits
it; if the former, he can state his denial in three
words; if the latter, I ask him to explain the

fact.

Philosophical physicians have before now rendered immortal service to the cause of physical science; and, should the opportunity arise of making some small return for this service, it is not the philosophical physician who will scorn our offered aid. The germ theory of disease, says

The beam of light enables us to answer this question also. I have had a chamber constructed, the lower half of which is of wood, and the upper half of glass. On the 6th of February this chamberwas closed, and every crevice that could admit dust or cause a disturbance of the air was carefully stopped. The electric beam, when sent through the glass, showed the air at the outset to be loaded with floating matter. The chamber was examined almost daily, and a gradual diminution of the floating matter was observed. At e chamber was optically the end of a week: empty. The floating matters, germs included. had wholly subsided, and the air he'd nothing in suspension. Here again the ocular demonstration furnished by the luminous beam goes hand in hand with the experimental result of Pasteur.

Next comes Professor Lister's observation regarding the filtering power of the lungs. Turning once more to the luminous beam, we find that it declares air so filtered to be free from floating germs. Hence its inability to produce putrefaction, and the accompanying manifestation of animalcular life. Finally, as if to clinch the purely scientific experiments by a practical result, we find Professor Lister, actually employing cotton wool to ward off the atmospheric gerins, and, by its agency, keeping a large class of wounds sweet and pure. It is this intimate welding together of two independent series of observations that Dr. Bastian calls indirect evidence; it is my reliance on such evidence that fills him with "amazement." In matters of science I always sacrifice the emotions, otherwise I might permit myself a little amazement too.

NEW LUBRICATING APPARATUS FOR MACHINERY.-For nearly two years an invention has been practically tested on the Lancashire and Yorkshire Railway, from which a considerable saving in The peculiarity of the lubricating material is secured. and Co,, of Manchester, consists in the construction, invention, which has been patented by Messrs. Bauer in connection with the axle-box, of a chamber or receptacle for oil, underneath the axle journal a

The canal, to meet the requirements of modern commerce of all characters, should, the Scientific American thinks, be 50ft. deep its entire distance, and 500ft. wide at top, throughout the earth or valley cutting, and at least 150ft. through the mountain section. Without the most wasteful extravagance such a canal would not cost near 100,000,000 dols. The actual mountain section is not over three miles long, the rock is soft dolomite, and coralline, limestone, and gravel. The climate, unlike that of Panama, 18 Dr. Bastian, "appertains most to the biologist and which a disc, supported on elastic or yielding bearings, comparatively healthy, and there need be no such mortality as was witnessed in the coustruction of the railroad. 10,000 Chinese labourers would in five years add another to the great works of modern engineering skill.

the physician." Granted. But it is, nevertheless, true that the very best modern work connected with this subject has been executed, not by a biologist, not by a physician, but by a chemist. This is not the opinion of chemists only. Some of the The Suez Canal has cost over 80,000,000 dols., most eminent biologists of the present time speak and it is estimated to cost 20,000,000 dols. mors with no uncertain voice of the demonstrative to make it what was originally intended-that is, 'force of the experiments of Pasteur.

is partially immersed. This disc, owing to the periphery of its upper surface being pressed against the axle journal, is made to rotate when the axle is in motion, and a continuous supply of oil is thus transmitted to the journal and its bearings, the amount being governed by a doctor or plate, provided with a slot that embraces the disc, placed above the level of the oil. By this means a constant supply of the lubricant being insured, the possibility of the bearings getting hot, which often happens when the salve lubri cant is employed, is prevented.

LETTERS TO THE EDITOR.

{We do not hold ourselves responsible for the opinions of our correspondents. The EDITOR respectfully requests that all communications should be drawn up as briefly as possible.]

All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 31, Tavistockstreet, Covent Garden, W.C.

All eheques and Post Office Orders to be made payable to J. PASSMORE EDWARDS.

supposititious moon describe a complete orbit about
its primary, and so have convinced himself that it
had its origin and existence within the eyepiece itself,
and nowhere else.

A FELLOW OF THE ROYAL ASTRONOMICAL SOCIETY.

DARK LINES IN SOLAR SPECTRUM.
SIR, "T. A." should state his evidence. All I can
at present say is that his view is opposed to all the
evidence I know of. There are certain characteristics
we should expect to find in dark lines, caused by our
own atmosphere; certain others we should expect to
find in dark lines really belonging to the solar spec-
trum. We find accordingly that the dark lines may
be divided into two classes-the atmospheric and the
solar. Has "T. A. any reason to show why the
latter dark lines (all or any of them) should be placed
in the same category with the former?

R. A. PROCTOR.

JUMPING FROM A TRAIN IN MOTION. I would have every one write what he knows, and as much as he knows, but no more; and that not in SIR, A friendly correspondent points out what he this only, but in all other subjects: For such a perholds to be a mistake in my remarks on this subject. son may have some particular knowledge and expeOn looking at my letter, I find there is room for misrience of the nature of such a person or such a foun-conception. I was not referring to the case of one tain, that, as to other things, knows no more than who wishes (evil-disposed man to leave a carriage what everybody does, and yet to keep a clutter with "while the train is still in motion," against the laws this little pittance of his, will undertake to write the mande and provided by the authorities, but to one who whole body of physicks: a vice from whence great inwished to leap from a rapidly moving train. When convenienees derive ever it is possible, it is always well (as every one knows) their original. -Montaigne's Essays. to move in the same direction on terra firma as in the train. Even then, however, the motion with which one leaves the train is only forward with respect to terra firma, not with respect to the train; but where one has to spring from a train in rapid motion, and is quite sure of a fall, one may escape broken limbs by leaping strongly in a direction contrary to that in which the train is moving. Unfortunately, one cannot very easily do this. It is, however, useful to learn that when one is in an open carriage and the horses run away, one may effect an almost certain escape by springing sharply from the back of the carriage (supposing its construction suitable). I do not speak without having tried the experiment-not, indeed, in the case of a runaway trap. but from the back of a truck moving with considerable swiftness.

THE TELESCOPE.

SIR.-" Amateur" (2451) is confusing angular and linear magnitude, in a way nothing short of marvellous. In its existing form his' question admits of no answer; but the following considerations may possibly tend to help him out of his difficulty. The disc of the Sun subtends an angle of about 32, and 32′ (as Amateur" may discover by reference to a table of Natural Sines in the first set of mathematical tables he can lay his hands on), or the sine of 32', which practically coincides with the are, is 0093 of the radius of the circle on which it is measured, be that of what size it may. Now in most books on Optics, 10in. is taken as the standard distance of distinct vision; multiplying, then, 0093 by 10 we get 093in. as the length of a line subtending an angle of 3 at 10in. from the eye. In other words, if your correspondent will cut out a little disc of card, 093in. or roughly 1in. in diameter, and interpose it between his eye and the Sun at a distance of 10in. from the former, he will find that it will just hide the Sun from his view. If, then, we multiply, 093 by 40 we shall get, 372in.; or by 60, 558in. as the apparent diameter of the Sun with the powers he specifics. This is however only true at the one specific distance of 10in. from the eye; since, for example, the 3-72in. image would appa rently coincide with one of 16 32in., or the 558in. one with another of 33 48in. if the latter were removed to a distance of 5ft.; and, so far as "Amateur's" query, in any shape, admits of a response at all, this must be my reply to it.

tinctness.

a

"a Ursa Minoris "(2487), same page, is very much less difficult to answer, inasmuch as "a partially silvered speculum," and " a single plano-convex lens for an eyepiece" supply all the conditions needful for the production of any amount of fog, glare, or indisUrse" omits to say whether the plane or the convex surface of the single eye lens is turned towards the mirror; but under any circumstances. his friend ought to get some good Huyghenian eyepieces forthwith, always supposing that his speculum is worth them, and have that properly silvered into the bargain.

One can easily establish the general principle on which the matter depends. If any one will amuse himself by throwing stones from the back of a carriage, he will find that after a little practice he can so throw a stone in that direction, that the stone will fall dead still on the spot where it first touches the ground.

I see by your "Replies to Correspondents" that you think Mr. Beardsley should be answered. With all respect. I confess I am of another opinion. I think no student of science who values his reputation could seriously enter into discussion over such puerilities as those with which Mr. Beardsley has filled nearly a column of your space.

the rear seats.

following despatch through the Foreign Office from
Signor Visconti Venosta, one of the Italian Ministers :-
"Florence, February 26th, 1870.
'Sir,-His Majesty's Government took care to give
the greatest possible publicity to the notices contained
in your notes of the 20th June, 8th of October, and
22nd of December, 1869, relative to the Workmen's In-
ternational Exhibition, which is to be opened in Lon-
don next June.

I am glad to inform you that the iden of that exhibition has been most favourably received in Italy, and that in the most important cities of the kingdom no delay has taken place in constituting local committees which have spontaneously assumed the duty of encouraging it.

The King's Government, on its part, has in a special manner requested the Consultative Committee on solicit the participation of our country in that exhibiProvident Institutions and Labour to prepare and tion, and its Executive Committee has just published a code of regulations, copy of which is enclosed, explaining the course to be followed by Italian exhibitors..

You will perceive that independently of the subsidies which may be voted by the provinces, communes, and Chamber of Commerce, or accorded by private individuals, the exhibitors are entitled to gratuitous transport by sea of the articles for exhibition, and to the reductions usually granted in similar cases by the railway companies.

I must add that the King's Government intend instituting an Italian commission in London, which will provide for the reception and placing of the articles and for their reconveyance to Italy.

I am convinced that this commission will receive the support of the British authorities charged with the direction and regulation of the exhibition, and in this conviction I avail myself, &c..

"(Signed) VISCONTI VENOSTA." The following reprint from the Daily News will give a good idea of the intentions of this exhibition: "It is intended, as no doubt most of our readers are aware, to hold a Workmen's International Exhibition in London, in July, 1870. The distinguishing features of the scheme are

"1. All articles exhibited will be signed with the name of the workman by whom they are made.

2. In those manufactures in which division of labour prevails, workmen will be invited to exhibit specimens of that particular branch of work in which they are severally engaged. Thus, for instance, a watch or a piano might be exhibited, showing in a complete series the various parts on which workmen are severally employed, and the various steps by which it approaches completion. Each workman will thus have the opportunity of showing his skill in his own special department, or of calling attention to any improvement in the manner of manufacture he may wish to introduce, and the public will better understand the whole process of construction through which the completed article has passed. 3. Workmen are invited to combine for the production of the same article. In all cases the article will bear the workman's signature.

to arrange these in such a manner that the English and the foreign process may be compared with each other, and lectures given in explanation of the relative advantages possessed by the different methods. 5. In the same way, for the purpose of comparison, when the manufacturing process is of such a character that it cannot be seen in operation, an endeavour will be made to show, side by side, by means of drawings and models, some important variations in the methods pursued in different countries.

It is one thing to exhibit the evidence on which the earth's figure, &c., depends, and quite another to take. To show the various processes of manufacture, and up the challenge which "charlatans and enthusiasts" are ever ready to throw down. Surely your readers must all see for themselves that Mr. Beardsley's letter needs no answer. If we spring from the floor of a railway carriage, we are not forthwith flung against find it more difficult to throw a ball to a passenger on A passenger on a rear seat would not a front seat than the latter would find it to return the compliment; yet for Mr. Beardsley's argument these and all the thousand evidences derived from daily experience must be forgotten. The real fact is, that it is not with the teachings of astronomy he contends, but with the familiar principle known as the second law of motion. It would be absurd to reason with him. If he were to point out any flaw in the reasonings in my paper on the earth, I should feel bound to set matters straight; but as a matter of fact, he has gone out of his way to deal with things I have not touched on in my paper, conceiving as I did that to explain such matters to those for whom the ENGLISH MECHANIC is primarily intended would be to carry coals to Newcastle. R. A. PROCTOR.

"The Right Hon. W. E. Gladstone, M.P., is the president, supported by noblemen and gentlemen of all parties as vice-presidents; the executive committee consists both of men of position and artisans, assisted by a handsome guarantee fund and good list of subscriptions. An agreement has been made with the Agricultural Hall Company for the use of their hall at Islington, in which there is ample room for exhibits, and which will contain 30,000 visitors. Very considerable progress has been made not only in this country, but in foreign countries. Side by side with the contributions of our own country will be the productions of the French artisan, of the thoughtful German, of the artistic Italian, of the persevering Dane, and of our American cousins. "Local committees have been formed at Venice,

I may inform Mr. Baguley (2498), p. 95, that any optician whatever, would make him a Ramsden's eyepiece. Slater, of 138, Euston-road, London, would be a very good man to go to, were he a little less dilatory; or Baker, of 243, High Holborn; or Murrell, of 5A, Mitchell-street, St. Luke's, both in London, might be depended on. From 128. to 15s. would be a fair price to pay for it. Two ways only occur to me in which Mr. B. could deepen the colour of his sun shade. The one is to ENGLISH MECHANIC MUTUAL IMPROVEMENT Verona, Florence, Turin, and Genoa. The Syndic of have a piece of green glass cemented on to his present red one; the other is to smoke its internal surface over a candle. The latter is the more feasible, as the first would render the eyecap inconveniently thick. It is impossible to re-colour the glass, but Baker would take it out and replace it with another of any tint your correspondent chose for about a shilling.

A FELLOW OF THE ROYAL ASTRONOMICAL SOCIETY.

ASTRONOMICAL.

SOCIETIES.

SIR, The letter in last issue but one, on ENGLISH MECHANIC Mutual Improvement Societies has given, no doubt, great satisfaction to many subscribers of our paper besides myself. The same thought which has been so vividly depicted was also in my mind, but true, in a dormant state, waiting, like the worm for the spring, to emerge from its cover. Will you therefore allow me to take a part in the movement, and propose to the subscribers living in Manchester to assemble one night this week, to discuss the subject namely, the formation of a Manchestrian ENGLISH MECHANIC Mutual Improvement Society, I feel conLevinced that much benefit would be derived from such a society, and would in some measure be a reward to our indefatigable editor, in effecting prosaically the truth in the editorial article, "Ourselves and Our Subscribers."

SIR,-"Gimel " (2448), p. 94, speaks as though Verrier had both computed the mass and distance of Neptune, and made the optical discovery of it as well in his own person; at least so I interpret the words by calculation and observation," which he employs in connection with the name of the great French geometer. Le Verrier computed the hitherto unknown planet's place in the Heavens, as did Adams too; but the former communicated the result of his calculations as soon as he obtained them, to Dr. Galle, of Berlin, and he, searching in the indicated region, at once found Neptune; so that Dr. G. was what would be vulgarly called the discoverer of the new planet. "Gimel" may get some idea of Adams's process from Vol. 16 of the" Memoirs of the Royal Astronomical Society," and from the" Supplement to the Nautical Almanac for 1851."

Did it never occur to "H. A. C." (2452), p. 94, that the very circumstance of his pseudo Satellite of Venus disappearing with a change of eyepiece was, in itself, a very suspicious one? The probability is, that had he only turned the 240 eyepiece round in the tube, while watching the planet, he would have seen his

Having been fortunate enough to make
ments with the landlord of the Dog and Partridge
Hotel, I suggest that we meet there on Friday evening,
29th April, at 7 o'clock, when I hope to meet many
subscribers.
A. TOLHAUSEN, Manchester.

Palermo has announced that the artisans of that city shall have their contributions forwarded to London at subscriptions have been raised to pay the expenses of the expense of the commune. In the Italian cities transit, &c. The exhibition has the hearty support of General Garibaldi. The secretary of the local comand companion, Signor Dolfi, who continued his efforts mittee at Florence was the general's intimate friend until his lamented death. He has been succeeded by Signor Dassi, the president of many workmen's instiHon. A. H. Layard, the chairman of the committee at tutions. Through the hearty exertions of the Right Venice, and Hon. Secretary Dr. Errara, twenty picked exhibition, and the committee in London will endea

Italian artisans will be sent to London to visit the

vour to extend their visit to Manchester, Leeds, Birmingham, and the other great centres of manufactures in this country. In Germany committees are arrange-Mayence, Darmstadt, Offenbach, Stutgard, Carlsruhe, being formed at Berlin, Frankfort-on-the-Maine, and Munich, at Pesth in Hungary, and at Warsaw in Poland. The Baden contributions will be collected at Carlsruhe, and there exbibited, and then forwarded to London at the expense of the State. The Wurtemburg Government has voted 10,000 florins for the use of the committee at Stutgard, for the expense of transit, and to give subscriptions to workmen desirous of visiting the exhibition. Committees are also formed at Copenand energetic committee is formed at New Orleans, hagen, Hamburg, Rouen, and Brussels. A very active and contributions are promised, and the manufacture of sugar will be exhibited, as the makers of this article claim to have reached a great degree of perfection. The South Carolina State Agricultural and Mechanical Society have placed themselves at the head of the

WORKMEN'S INTERNATIONAL EXHIBITION,

1870.

SIR,-As the interest in the Workmen's International Exhibition is daily increasing, a few words upon the subject may be acceptable, and perhaps useful, to many of your readers. The following despatch, which has been received by the council through the Foreign Office, will give an idea of how warmly the subject has been taken up upon the Contineat:

"The council of this exhibition have received the

The

movement in the Southern States of America.
Earl of Clarendon, her Majesty's Secretary of State for

Foreign Affairs, addressed a circular letter to all her Majesty's ministers, envoys, and consuls abroad, requesting them to give publicity to the exhibition, and to promote the formation of committees, and to assist with all their influence the objects of the council of the exhibition. The principal effect of this circular has been to convince the council that many places would have been entirely excluded unless agricultural produce and raw material used in manufactures were admitted. The council, therefore, have decided not to exclude those articles, and through the energetic help of our consuls, agricultural produce, &c., will be exhibited from Patras (Greece), Algiers, Naples, Cagliari (Sardinia, New Orleans, Lisbon, San Francisco, Corfu, Madeira, Galveston (Texas), Rio de Janeiro, Mobile, Lima (Peru), San Jose, Costa Rica, Norway, Havana, Para, Rosario. Bogota, and Monte Video. To meet the views of the Russian Government the council will endeavour to make arrangements so that the articles exhibited in th Workmen's Exhibition at St. Petersburg in May next may have place in the London Exhibition. The council also have been in communication with the French Government, and they have every reason to hope that an admirable display of French workmanship will be exhibited. The Duke of Argyll, her Majesty's Secretary of State for India, has announced that a selection representing Indian art manufactures shall be exhibited, and the expense of fitting shall be defrayed by the department.

"To meet these very energetic efforts made in foreign Countries, seventy local committees have been formed in the United Kingdom. As an example, the city of Belfast has a very active committee, of which Mr. W. Kirkpatrick (of the Northern Whig office) is the able and efficient secretary. Avery ample subscription has been raised to meet the current expenses, and to pay part, or the whole, if possible, of the carriage of articles to London. The committee has also received the countenance and support of the leading manufacturers, who have promised to give every facility to workmen in their employment who may express a desire to produce articles for the exhibition. It is hoped that the artisans of this country will make a most determined effort, so that the Workmen's International Exhibition of 1870 will not only be a display of the best foreign workmanship, but an exposition of the talent, industry, and manipulative skill of the British workman.

To further the objects of this exhibition, the King of Wurtemburg has directed that his name be added to the list of guarantors for the amount of £100. The President of the Republic of Peru has directed that all the expenses of transit of articles to the exhibition, with the expenses of the Central Committee at Lima, such as printing, postage duties, &c., shall be defrayed by the State. A handsome subscription has been forwarded to the hon. secretaries of the exhibition by the British residents at Buenos Ayres."

It has also been proposed to open workshops in the exhibition building, and to give prizes for the highest

skill shown in the use of various tools.

In the scholarships, so generously given by Mr. Whitworth for mechanical science and practice, about an equal amount of marks are to be given for theoretical knowledge and for manual skill.

The examination for these scholarships, which is to test the manual proficiency of the candidate, consists of two parts. In the first part the candidate is required to produce certificates, to exhibit work specially executed for the occasion, &c.; in the second part he is required to show a knowledge of various tools, by the performance of one or more of the following pieces of work :

The Axe.

in diameter. Engraving-To engrave on glass and stone and metal; the engraver working from a copy or inventing the design, which would be required to suit certain circumstauces, to be made known at the time. Modelling-In wax, clay, leather, &c., the designs to be original and from copies. Carving-In wood and stone. Inlaying-In metal, wood, and stone. Designing-Of articles belonging to the textile trades, the glass trade, the porcelain trade; the designs to be original, and to snít special circumstances to be made known at the time.

The rules to be observed by exhibitors are as follows:

1. The exhibition to be opened on the 7th July, 1870, at the Agricultural Hall, Islington, London. 2. No charge will be made for space.

3. Space will be allotted to exhibitors by the council of the exhibition.

4. All articles must be brought, exhibited, and removed at the risk and expense of the exhibitors. 5. All packages arriving at the exhibition in the absence of the exhibitors or their agents, will be opened by the servants of the council with the greatest care, but at the risk of the exhibitors.

6. Articles once exhibited must not be removed during the continuance of the exhibition, except by permission of the council.

7. All property not removed within seven days after the close of the exhibition will be dealt with as the council may direct.

8. Exhibitors may appoint persons, subject to the council's approval, to take care of articles exhibited by them, or to explain them to visitors.

9. The council will supply counter, wall, and floor space, but any special fittings must be furnished at the exhibitor's expense.

10. In cases where a number of workmen combine to produce any object, the name of each workman must be given, and the portion executed by each specified. The same rule will apply to all articles exhibited by manufacturers and employers, which will be admitted subject to this regulation.

11. All articles intended for exhibition must be approved by the council, or such officers as they may appoint, the council reserving to themselves the right of rejecting any articles which may be unsuitable. 12. All articles must be delivered at the Agricultural Hall, Islington, between the 20th of May and the 25th of June, 1870.

The Board of Trade are preparing a bill for the protection of inventions shown at the exhibition, so that inventors need entertain no fear of their inventions being pirated without their being able to help themselves, as the mere fact of the invention being exhibited in this exhibition will be a provisional patent in itself without further expense or trouble of any kind whatever.

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SIR,-The many erroneous notions that prevail among inventors in regard to this form of locomotion will ever prevent its general adoption, the foremost of which is, that speed cannot be obtained without great expenditure of the moving power, an axiom true in regard to stationary mechanics, but one that has no place with locomotive vehicles.

The great obstacle of rough roads is best overcome by excessive speeds, not by slow motion and main force, especially as muscular strength will endure for a far longer period with slow than rapid motion

In all the velocipedes and bicycles now in use the only gain in speed over an ordinary walking pace is the difference between the circumference of the driving wheel and the walking tread, so that in order to gain a speed of more than 7 or 8 miles an hour an impossible rapidity of muscular action is required, and until from 15 to 20 miles and upwards be possible, velocipede riding will never become generally a mode of locomotion. Fortunately, we are now in possession of a means of obtaining any rate of speed, limited only by the resistance of the atmosphere at high velocities, with slow muscular action. By the use of indiarubber tires all carriages are rendered independent of bad roads. The tires must not, however, be in the form of thin plates, as proposed by the "Phantom" Wheel Company, but must have a depth of between multiplying the motion of the treadles by a wheel and two or three inches in order to be effectual. Also in pinion in the proportion of four or six to one, stout prevent all clatter and friction, when with 4ft. india-rubber tires to both wheel and pinion will driving wheels, loose on their axles, 30 miles may be readily attained, while the muscular motion of the drivers' legs will only be equal to that of walking at universal up and down vertical tread is also a great the rate of two or three miles in the same period. The mistake, for it can only be compared to running up the Monument stairs with half-a-hundred on one's back; whereas, if the strength of the legs be used in the horizontal position it is found to be equal to a one-horse century, and many others, have successfully withstood power. For a strong man, such as Topham of the last the pull of a brewer's dray horse. Some inventors put "Tod-forward the absurd idea that the weight alone of the driver should actuate the propulsion. Others again would use both legs and arms; in fact all the muscles of the body at the same time, rapidly producing an exhaustion that no human frame could endure for many minutes.

The space allotted to English exhibits is being cations is April 25th, so that intending exhibitors will rapidly taken up, and the last day for receiving applido well to make early application to the hon. secreStrand, between 10 and 4. Every information, space taries of the Workmen's International Exhibition, 150, forms, &c., can also be had on personal application to the St. Mark's Club, 11, Brown-street, Duke-street, W., stamped directed envelope to London, between 7 and 10 p.m.; or by letter enclosing ROBERT BURGESS, Local Secretary, 22, George-street, Oxford-street, W., London.

EQUATIONS.

SIR, -We have had several queries lately upon quadratic and other equations. I beg to forward a. To square up a block of wood 1ft. long and 6in. solutions of equations redueible to quadratics. hunter," p. 171.

in diameter.

b. To make a spoke for a cart wheel.

c. To shaft an axe.

d. To cut out wheel spokes ready for fitting into nave.

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b. To make a pair of smith's tongs.

a. To weld or join together two pieces of iron in. square.

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d. To make a pick.

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e. To make the head of a hammer.

e. To make 2ft. gin. chain with hook and ring.

f. To make a horse-shoe complete.

g. To cut off and draw out chipping chisel or drill, and afterwards harden.

h. To make a pair of small callipers.

i. To make a pocket square.

It is with this part of the examination that we are here concerned. We are impressed with the soundness of judgment which has led Mr. Whitworth to give weight to manual as well as to theoretical proficiency in the examination, and it seems to us that the forthcoming exhibition would offer to workmen of different countries an interesting opportunity of competing in the skilful use of the most important tools.

Besides the tasks of work required from candidates for Mr. Whitworth's scholarships, many others may be suggested, such as:-Joining-The putting together a door. Turnery-To turn in ivory seven balls, one within the other, the outer one not to be more than 14"

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It is scarcely necessary to allude to the trotting velocipede, or that most glaring absurdity of propulsion by means of a spiral spring, patented by M. Ferdinand Constant Colney, of Paris, who makes the additional blunder of after having obtained circular motion, introducing the crank system. His spiral apring would require a considerably greater power to wind it up than would be required to propel the carriage direct. A light carriage for 30 miles an hour with slow treadle movement is figured and described in a former number of the ENGLISH MECHANIC, under the title of the "Velocifere." HENRY W. REVELEY, Reading.

SLATER'S ELECTRO-MAGNETIC MACHINES. SIR,-A description of Mr. Slater's newly-patented electro-magnetic machine may probably interest your readers, so I send an abstract of the specification. The said invention relates more particularly to various improvements in the construction of electro-magnetic machines as motors, and in the construction and mode of exciting batteries, and in the application of such motors and batteries to various useful purposes. These improvements consist, firstly, in the construction and arrangement of electro-magnetic machines, and in transmitting the force obtained through these improved batteries and magnets, and rendering such force available for useful purposes either through a reciprocating or rotative movement. Mr. Slater constructs his magnet of the form shown in Figs. 1 or 2; Fig. 1 is of the horse-shoe form, circular in section, but swelled out at the poles of the magnet at the end of each limb, so as to give a greater surface for the armature to work on, and otherwise for the increasing of the surface of the armature and power of the magnet. A, A, is the magnet, either made of solid wrought iron and circular in section, or as in Fig. 2 built of sections of flat soft wrought-iron plates, but also swelled out at the poles of the magnet. Either one magnet is used, as in Fig. 3, or more than one (in a series) as in Fig. 4, increasing substance so as to obtain a greater attractive force for the armature to be attracted against by the "moment of force" alternately, Bis the armature of a compound form built up of a series of wrought-iron plates, as shown in section, Figs. 1, 3, 4, 5. The outer edge of the arma

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ture works on the outer edge of the poles, or nearly so, of the magnet, and not absolutely in contact when raised from the poles, as shown at C, Figs. 3, 4, and 5; each end of the armature having journals D to work on, to keep it always in its proper position, so that the heel of the armature may be nearly into contact at all times with the poles when raised from the magnet. Attached to each of the armatures are levers E and E', to communicate the electro-galvanic force from the armature to the connecting rods F, Fl, thence to the cranks G, G. which are attached to the running shaft H, on to which is affixed fly wheels I, so as to maintain the momentum of the machine. There is an arrangement on the main shaft or on a separate shaft driven by the former, on which is placed commutators" of metal J, J, which revolve with the shaft, and on which the conducting wires K, K', form the battery work, or in other words are in contact; but on these revolving discs or commutators are inserted pieces of ivory or any non-conductor, so that as the commutators" or "discs" revolve the force from the battery is laid on to the magnet when the armature is raised to the angle required, and when attracted downwards the wire passes on to the non-conducting surface and releases the armature, when it is raised to the position C again, and so on in succession for any number of strokes per minute. By this repeated laying on and taking off the force, the armature B rocks up and down, the faces of the armature coming into contact alternately with the faces or poles of the magnet, producing the reciprocating movement as described. The power of the machine is increased in a ratio not yet ascertained in practice by the introduction of the compound armature. but it has been found to be so material that the solid iron armature has teen abandoned in consequence. In transmitting motion to the crank shaft from the armature B through the lever E and connecting rods F and F', it will be readily seen that the crank is in its worst position for the transmission of dynamic force to the rotative shaft at the time when the armature is receiving in greatest attractive force from the magnet, but in order to obviate this difficulty the connecting rods are made of an elastic material, either of caoutchouc, or of helical springs of steel wire, as shown in Fig. 7, but supported with extending sleeves in the inside in sections like a telescope slide, so that when the armature closes on the magnet and the force is disconnected, the connecting rod will assume its normal length again before passing, or at the time of passing the lower centre of the angle of 90°. The branches of the magnet are coiled left and right with its equivalent of insulated copper wire, so that each end of the horse-shoe may have its opposite polarity, the ends of these wires L, L are attached with the negative and positive poles of the improved battery. Electro-magnetic force in electro-magnets of this kind is due to the induction current, which the development and disappearance of the magnetism of an iron core indicated by the insulated spiral snrrounding it, which is termed excited magnetism. Much depends also on the area of the section and faces of the two ends of the limbs of the horse-shoe, which are the poles. In his improved magnet Mr. Slater swells out the end of such limb of the magnet at the poles, as shown in Figs. 1, 2, 3, 4 and

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5, so as to increase the surface of the poles, and also allow more attractive force and surface for the armature to work against. He also constructs a single machine, as shown in Fig. 3, where a, a, is the frame or support of the machine, A the magnet, B the armature, and lever E, the connecting rod F. and the fly wheel I. The commutator, or disc, for laying on and off the fluid from the battery, may be placed on any convenient part of the machine.

Another form of working a double compound armature is shown in Fig. 5, where the magnets A, A, are placed horizontal, or nearly so, and the armature B works between them, and the leverage for the connecting rod d to transmit the power is taken off at the point e, so that the armature would rock on the bearing or journal D.

In regulating the action and velocity of such machines to suit various loads, a governor of very simple construction is used, by placing a small plunger "cataract" governor between the battery and the magnet or magnets, such machine to have a valve at the bottom as the plunger ascends to let in fluid from the small cistern, the regulator being a valve or tap to let the water out slow or fast, as the case may require. This will act on a small mercury bath in which the conducting wire is immersed, the immersion being regulated by the governor as before described, which regulates the speed in proportion to the load on the machine at the time.

In his improved battery, and also improvements in the manner of using such batteries with one or more cells, as shown in section Fig. 8, Mr. Slater uses excitants different from those commonly used, especially when a uniform current is required. As the Bunsen battery is of similar construction, it will be necessary here to explain the difference between his improved battery and that of the former. Instead of using zincs in the outer cells and carbon in the inner cells, he uses soft iron plates or cylinders in the outer cells in combination with his improved method of exciting such metals as described. At the same time he uses the carbon in the inner cells, but with a difference also in his exciting solution as described. The excitant he prefers is a saturated solution of nitrate of soda or nitrate of potash. The former is found best and cheapest. In this solution the plates of iron (if a battery of flat plates), or cylinder of iron (if for cylindrical cells) are placed in the outer solution, as in section Fig. 8. Then the carbon or graphite g is placed within the porous cell h, which cell contains nitrous acid of the specific gravity of 1'60, or any weaker fluid containing in solution nitrous or nitric acid; but the stronger acid is preferable. The acid in the porous cells h should be about 1in. higher than the solution in the outer cells in which the iron cylinders are placed. The infiltration, or exos, or endosmosis process through the porous tubes or cells h keeps the outer solution containing nitrate of soda constantly supplied with acid, preventing it from becoming alkaline. When the iron and carbon are properly excited iu their cells, the constant action of the battery can be maintained by adding about one-sixth to one-third of fresh nitric or nitrous acid daily. This partly exhausted acid solution is mixed with the nitrate of soda and used for exciting the iron in the outer cells,

adding a small quantity daily in accordance with the amount of work done.

Another method of compounding a useful excitant is by using nitrous and muriatic acids, the former of the specific gravity of 160, and the latter about 1-200, in equal proportions (by measure) to be used in the carbon cells, and the nitrate of soda as before described in the outer cells. Or a very powerful current is generated when nitric or nitrous acids are used alone or combined with sulphuric or muriatic acids in small proportions in the cells with the carbon, and dilute nitric acid is used in the outer cell with the iron. When the nitrate salts are not used, nitric acid is used in the outer cells. The filtration through the porous cells will keep the outer excitants for the iron nearly uniform in strength until the iron solution is almost of a pasty consistency. Where great intensity is required in batteries, especially for telegraphic purposes, the saturated solution of nitrate of soda or potash only is used both inside and outside of the porous cells. Furthermore, if an increase of power is required without adding to the number of cells in the process of working in any especial case, then to the nitrate of soda solution in the porous cells is added about one-tenth part of weak acetic acid or common vinegar. D. F. K.

COMBINED PUNCHING, SHEARING, UPSETTING, AND STRETCHING MACHINE. SIR, I send you drawings of a very ingenious and useful little machine of American origin, which has been lately introduced into this country by Messra. Towle and Harding, of 98, Newgate-street. This machine, which is constructed by Messrs. Reed and Bowen, of Boston, U.S., is intended for shearing, punching, bending, and shrinking or stretching tires or hoops, and when constructed in the form we illustrate is adapted for being worked by hand power. The machine, in fact, although capable, when worked by one man, of cutting easily bar iron 24in. by in. or 4in. by in., weighs only 35016.

Referring to Fig.1,it will be seen that the main frame A of the machine, consisting of the two sides and the tep and bottom is cast in one piece, the cam B being placed between the two sides and hung on the pin C. The first lever D works into this cam, and is hung on the pin E, the knife F, for shearing, being attached to this lever and the knife F2 to the main frame A, The second lever G is connected to the first lever D by the straps H, and to the main frame A by the straps H2. The third or hand lever I is connected to the lever G by the straps J, and also to the main frame A by the bolt K. This forms a very powerful arrangement of levers, giving with 200lb. on the hand lever a pressure of over 52,000lb. on the shears and 72,000lb. on the punch. The straps H, H2, and J are in pairs, one on each side of the machine.

The operation of shearing is performed by placing the metal to be cut between the knives F and F2, and then bearing down on the hand lever I. The tire shrinker and stretcher consist of a block L, which is part of the main frame A. On the back of this block there is a projection M, against which the tire rests, and which is provided with teeth at the end so as to

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