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be, at such a time, to move the legs 'under the shaft towards the belly of the horse, or take them off altogether.

The next objection will be the appearance; but, in carts for conveying burdens, elegance is not consulted, but utility alone. The legs will neither be in the way of the carman nor the horse, but, in case of accident, will prove fortunate to them both.

I am, Sir, yours, &c. A GOLDSMITH'S APPRENTICE. No. 14, Frith-street, Soho, Westminster.

STEAM CARRIAGES.

It is stated in an article of news from Copenhagen, inserted in all the newspapers, that Matthew Broemark, a learned Danish Mathematician, has invented a new Steam Carriage, which" can be easily guided, and travels at the rate of fourteen leagues an hour!!!" The first experiment, we are told, "was made sixty leagues from Copenhagen. The carriage, loaded with passengers, set out at half an hour past eleven from the place where it was built, and arrived at the gates of Copenhagen at a quarter before five." M. Broemark, it is added, intends paying a visit in his carriage to Paris. We hope he will cross the Channel before his return home, and afford us ocular evidence of what, we must confess, appears to us at present rather an exaggerated statement.

A steam carriage has also been launched in the United States, which does wonders, though nothing like what is reported of M. Broemark's machine. The following account of it is given in a letter from Edgar Court-house, Illinois :

"I have had the pleasure, with fifteen or twenty other gentlemen, of viewing and closely examining a large model of a steam carriage, lately invented and put in operation by Mr. T. W. Parker, of Edgar county, Illinois, late of Vincennes; and it is the opinion of all who have examined it, that it cannot fail to operate well, and that there is apparently no fault to be found with it. Mr. Parker

has sent to Washington city for a patent. "I shall attempt to give a short description of this carriage. It runs on

three wheels, two behind and one in the centre, which wheels, with their axles, are united together by slip-sleeves, which, in turning, can be slipped out or in at pleasure, and by the fore wheel can be steered remarkably easy, with a windlass similar to that of a ship. This carriage is very simple in every part, and very light. The construction of the engine is altogether new, and the power is given by a double cylinder, with pistons working at both ends, which are attached to the crank of the fore and after wheels. The cylinder is supplied by a tort,about as large again as as the cylinder, which is made of copper or cast iron, and which is placed in a small air furnace. The tort is supplied by a forcing-pump and a copper pipe, running through the tort, perforated with holes of the size of a small needle, or about sixty to a square inch. At every motion of the forcing-pump, there is a small quantity of water forced from this pipe, and is immediately converted into steam (the tort being very hot), which passes from the tort to the cylinder.

"Mr. Parker gives it as his opinion, that a carriage of 20 tons burthen will not require more than 20 or 25 bushels of good coal per day; and that 300 gallons of water will produce 30 revolutions each miunte on an eight-feet wheel, at which rate the carriage will travel, on good turnpikes, upwards of 200 miles a day. One man and a boy will be sufficient to tend upon a carriage of this pleasure carriages as well as for burden. kind; and they can be made light for This carriage will perform her duty without the aid of the European rail-roads, on any good turnpike-road, and will be completely manageable up hill or down.”

they are taken from the forger to the hardener, without undergoing any intermediate process; and such is the accustomed routine, that the mischief arising has escaped observation. The art of forging produces a strong scale or coating, which is spread over the whole of the blade; and, to make the evil still more formidable, this scale or coating is unequal in substance, varying in proportion to the degree of heat communicated to the steel in forging; it is, partially, almost impenetrable to the action of water, when im mersed for the purpose of hardening Hence it is that different degrees of hardness prevail in nearly every razor manufactured: this is evidently a positive defect; and, so long as it continues to exist, great difference of temperature must exist likewise. Razor blades not unfrequently exhibit the fact here stated in a very striking manner: what are termed clouds, or parts of unequal polish, derive their origin from this cause, and clearly and distinctly, or, rather, distinctly, though not clearly, show how far this partial coating has extended, and where the action of the water has been yielded to, and where resisted.

It certainly cannot be matter of astonishment that so few improvements have been made in the hardening of steel, when the evil here complained of so universally obtains, as almost to warrant the supposition that no attempt has ever been made to remove it. The remedy, however, is easy and simple in the extreme; and so evidently efficient in its application, that it cannot but excite surprise that, in the present highly improved state of our manufactures, such a communication should be made as a discovery entirely new.

Instead, therefore, of the customary mode of hardening the blade from the anvil, let it be passed immediately from the hands of the forger to the grinder; a slight application of the stone will remove the whole of the scale or coating, and the razor will then be properly prepared to undergo the operation

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of hardening with advantage. It will be easily ascertained that steel, in this state, heats in the fire with greater regularity; and that, when immersed, the obstacles being removed to the immediate action of the water on the body of the steel, the latter becomes equally hard from one extremity to the other.

To this may be added, that, as the lowest possible heat at which steel becomes hard, is indubitably the best, the mode here recommended will be found the only one by which the process of hardening can be effected with a less portion of fire than is or can be required in any other way.

These observations are decisive, and will, in all probability, tend to establish in general use what cannot but be regarded as a very important improvement in the manufacturing of edged steel instruments.

WOODEN CHURCH CLOCKS.

SIR,-Being lately at a clockmaker's shop, and inquiring the price of a large turret or church elock, I was informed it varied from sixty pounds to six hundred. This appearing to me an enormous sum, it occurred to me whether it was

possible to substitute wooden clocks in particular cases for those of iron, especially for village uses. This appeared to me possible, as the common wooden or Dutch house-clock keeps as good time, for domestic purposes, as a brass one; but, never having heard of a wooden clock of any magnitude, I would beg any of 'your Correspondents to decide on the utility of such an article of me chanism, and to state the objections, if any; for, if few, these articles may probably be brought into use,where, from the great expense of those of metal, many villages and small towns are utterly destitute of that valuable public and private regulator.

SIR, I am one of the "two persons" alluded to by C. Eagland, in No. 76, page 307, of your work; and he failing (as he says) to convince me of the truth of his theory, dured me subsequently to answer his letter, otherwise I should not have attempted such a thing, for fear of cutting but a poor figure in print; but should. I answer him" properly,' in a mechanical sense, 1 trust all "faults of style" will be excused.

If a deal plank be placed in scale A, with or without a fulcrum, as in the following diagram, and poised with a weight in scale

B

B, and weights, say 20 stone, be placed on the plank at each of the points, C and D, to poise each other, 40 stone in scale B will balance the whole. But if, instead of the 20 stone at point C, a man of 12 stone stands, pressing upwards under the fulcrum, with a power of eight stone, he will restore the equilibrium of the plank and beam, with 40 stone opposed to 32. If the weights are removed from D to E, and the man to F, pressing at point G of the beam, the same power will produce only half the effect, and at all other parts of the beam in proportion, on the wellknown' principles of the lever, without forcing the scale "obliquely outward,"

Or "

elongating that arm of the beam." The same effect may be produced by fixing a pulley to the cieling over the beam, and another to the floor under the scale, with a cord tied to the beam, passing round the pulleys, and through a hole in the centre of the scale, for the man who stands in it to pull by.

I am, Sir, yours, &c.

J. B.

SIR,-Although have been a subscriber to your interesting and valuable Publication from the beginning, yet as my bookseller sends it to me in parts, two or three at a time, I have only recently noticed the various communications of your different Correspondents

upon the subject of the apparently singular property of the Balance, first alluded to by C. D., page 224. It has often struck me as unaccountable, but I never paid much attention to it till I observed it noticed in your Magazine. A little reflection, however, solved the difficulty, and I purposed sending you my solution of it, when I observed the letter of your Correspondent, G. B., page 234, which before had escaped my notice. His explanation perfectly corresponds with that which I had intended to have given; I should not, therefore, have troubled you, but from one or other more recent communications, which deny its cor

rectness.

And, first, I will make one or two observations on the letter of S. Y., page 278. It is evidently written by a young engineer; one more experienced would have advanced a more plausible explanation of the property in question before he had so intemperately opposed G. B. I confess that I see nothing in the style of the latter which warranted such language. It is not in this way that science is promoted. I, however, maintain, that the reason assigned by G. B. is the cause of the effect mentioned. I dare say, G. B. never supposed that a pressure, however great, exerted in the way S. Y. describes, would increase the actual weight; but still, in proportion to the pressure, will the scale preponderate more or less. It always gives me much pleasure to read the communications of such Correspondents as C. Eagland, page 307; his letter forms a pleasing contrast to that of the young engineer. But it will be found from experiment, that the pressure exerted by a person in the scale against the beam is not sufficient, in its reaction upon the scale, to throw it so far out of the perpendicular as to produce so great a preponderance. In fact, the pressure may be made in such way as not to produce this effect in the slightest degree; for let it be exerted against a fixed object to the same degree, in the same direction, and the effect will not be produced. It appears to me, that the reason assigned by G. B. is sufficient, and philosophy teaches us not to multiply causes. If I press upwards with a force of six pounds, this force is also exerted in a downward direction--action and reaction being equal and contrary. Now, supposing half the beam to be two feet, and that I press at the centre of this, it is evident that my downward pressure is, at the end of a lever, of twice the length

of that upon which the upward pressure is exerted; the preponderance follows of course. I do not know if I have made my explanation sufficiently clear, but it will be seen that it coincides with the view taken of it by G. B.; and if you think it worthy a place in your Magazine, I shall feel happy to have been a contributor.

Iam, Sir,

Your obedient servant,

A CONSTANT READER.

93

SIR,-As a subscriber from the first commencement, and well-wisher to your very useful work, the "Mechanics' Magazine," I beg to offer it as my opinion, that the solution of the Balance Question, given by Mr. George Gregory, page 361, is founded on fallacious principles, and in what manner, I will endeavour to elucidate. Mr. Gregory writes with the technicality of a scientific mechanic, and I am therefore quite surprised to see him overlook in his position one of the first laws of the science, viz.-the line or centre of gravity.

Description.

'The letters ABCDEFGH, as above, bear reference, in a measure, to Mr. Gre gory's solution also.

If the point of suspension, A, be mechanically lengthened by the oblique direction of the man, to the full extent of his body in the scale, H, which would be at E; and supposing him to have forced himself completely horizontal with the beam, as GF, his preponderance of weight

must have increased as the beam was lengthened by his body to F, thereby destroying the well-known axiom, that the centre of gravity is always under the point of suspension; by which law, allowing the man's height to be six feet, the point of suspension would be extended to about three feet, or to letter I. This equally answers the question as stated in page 224. I am, Sir, Your obedient servant, Wiltshire.

F. J. M.

SIR, If I were to suppose myself capable of carrying conviction to the minds of those who are predetermined to reject without examination, and condemn as absurd, every opinion opposed to their own, I should, indeed, deserve the title of" presumptuous;" but I beg to inform James Yule, and your readers in general, that I do not write for the purpose of

making particular individual converts to my opinions, but merely to state those opinions, and the reasons why I entertain them; having done this, I conceive I have done enough. Those who are interested in the matter on which I write, will, of course, consider every thing they read or hear on the subject which is worthy of consideration. If they find my reasons good, they will most likely adopt my opinions; and if they deem other opinions better supported, I should be very sorry if they adopted mine. This is all the answer I mean to give J. Yule's attack upon my paper on the balance question. S. Y. 21st April.

(A Young Engineer.)}

P.S.-RAILWAYS.-Mr. Yule likewise disputes what I have advanced on Railways. I mean also to leave that paper to its fate; but I beg to inform that gentleman, that the question put to him in page 394, was sent to you previous to my writing the paper on railways, although the last-mentioned paper was first published; and as to my knowledge of the experiments of Vince and Coulomb, I candidly tell him, I know nothing more of them than what is published in Gregory's Mechanics; in which work I observe (vol. II. p. 21, third edition), "it was concluded, that the friction of hard bodies in motion is a uniformly retarding force;" and this is what I have supported; and, to prevent misunderstand

94

MEASURE OF FORCE FOR PERFORATING METAL AND OTHER SUBSTANCES.

SIR,-The measure of the force necessary to punch a hole through a plate of metal or other substance, may, perhaps, be interesting to some of your readers. I shall, therefore, trouble you with the result of some experiments made on that subject.

I had a good cylindrical steel punch made, and fitted to a guide or director, so as to move correctly to a cylindrical hole in a steel plate connected with the guide; with this instrument I was able to force cylinders of metal very uniform, and with little or no bur to the hole, both by simple pressure and by per

PURIFYING OIL FOR WATCHMAKERS.

SIR, Many processes have been recommended for purifying the oil used by watchmakers: A sand bath, washing it, boiling it, and exposing it to the sun in summer (as recommended by your Correspondent, p. 197, vol. in.) I must beg to say, however, that, by washing, oil is not to be freed from that intermixture which is injurious to the movement or the going of a watch; neither can it be purified by the application of heat.* Oils are, more or less, adulterated with gummy or watery particles, which cause the oil, when applied in small quantities, to dry on the plates like gum, or turn into rust: this I have found the cause of many good clocks and watches stopping. I have had clocks that have gone until the pinions have been worn to a thread by the friction caused by the rust. Sweet oil contains more impurities than the almond, and almond more than the olive. The best I could ever find for delicate machinery was the olive oil, and the way I purify it is as follows:-I put into a white glass bottle three parts of oil to one of spring water, shake them well together, and expose them to the frost. The water promotes the freezing of the impure particles in the oil, when the bottle may be turned upside down, and that which I consider to be the best oil will drain from the bottle.

I am, Sir,
Yours respectfully,

Broadway.

M. MONNOM, Watchmaker.

MR. DOWDEN'S GEOMETRICAL CON

STRUCTION.

SIR,-Permit a Tyro in Mathematics to observe, that the gcomemetrical construction, given in your 89th Number, of a parallelograin, said to equal the circle, does not correspond with the trigonometrical calculation there given. The per

*This is somewhat absolute, especially after the fact stated by our Correspondent, page 198, volume 1 EDIT.]