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MINOR CORRESPONDENCE, &c.

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years, I have been a traveller for knowledge. If my pursuits tend to the public good, I shall then be satisfied, and not deem my time misspent. -I remain, yours, &c. M. Saul.-Sulyard-street, Lancaster, June 3, 1829.

MISCELLANEOUS NOTICES.

Mr. Harvey's Dentatus. -We find that in our notice of Mr. Mason's Lecture at the Royal Institution, on Wood Engraving (No. 302, page 240), we committed an error, in stating that the wellknown picture of Dentatus, by Harvey, was formed of sixteen different blocks. The number was only seven. We take this opportunity of mentioning, that Mr. Mason has since repeated his Lecture at the London Institution, when he enriched it by many additional illustrations of great interest, and was again much applauded.

An

How to detect Cotton mixed with Wool.-At a late sitting of the Royal Academy at Metz, the following method of detecting the presence of cotton in woollen stuffs was communicated. ounce of pure alkali is dissolved in half a pound of water, and in this the suspected stuff is boiled for two hours. If the stuff is of pure wool, it dissolves entirely, and forms upon the surface a soap, which will pass through a fine sieve; but if, on the contrary, the stuff contains cotton, or any other vegetable fibre, it will not be entirely dissolved, but will show itself when thrown into the sieve.-Literary Gazette. A much simpler, and more expeditious method of detecting such intermixtures, was given in the first No. of the "Mech. Magazine." All that is necessary, is to subject the suspected article to the action of oxygenated muriatic acid; when the wool becomes yellow, and the cotton, if there be any, is rendered white.

MINOR CORRESPONDENCE.

"A Young Mechanic' would be greatly obliged to the Editor of the Mechanics' Magazine' to inform him of any treatise (either separate or connected with any other work) on the construction of musical boxes: also the best work on clock and watch making."-We do not know of any distinct Treatise on musical boxes; but there is a page or two devoted to the subject in Mr. Reid's "Treatise on Clock and Watch Making," which we have before had occasion to recommend to the notice of our readers, as comprehending ample information on everything connected with the art of Horology.

Mr. Saul's Fire Escape-Sir,-In No. 301, page 213, Mr. Baddeley states that I shall "be greatly surprised to learn that I am twelve years too late in the field." Mr. B. will find, by referring to my letter in No. 297, that it is dated on the same day that the account of Mr. Gregory's fire ladders was inserted in the "Mechanics' Magazine;" and before that appeared, I never heard or saw anything of Mr. G.'s inventions. It is quite clear, therefore, that I could not have made my invention from seeing Mr. G.'s. I have also referred to the "Repertory of Arts," for 1819, and 1 find no account whatever of a patent having been taken out for the speedy elevator. As Mr. Johnson has well observed, in vol. i. page 188, of the "Mechanics' Magazine," no one ought to" light his candle and put it under a bushel." And what man, I would ask, by giving a brother tradesman a light, lessens his own? I pretend not to infallibility, and hope to be judged with candour. I know well the difficulties and intri cacies of science, and am not without a hope that my labours may be of some use to others, in shortening the road through which, for several

INTERIM NOTICES.

We have received from P. M. W. a very complete refutation of the fallacies of J. B. C.'s "Objections to the Copernican System," inserted in cur last No. It shali have an early place.

Enes's paper is unsuited to our pages.

We have no recollection of the inquiry to which G. S. M. alludes. He will, perhaps, favour us by repeating it.

S. P. W. is requested to send to our publisher's for a note addressed to him.

We should have stated before, that the letter of Mr. W., of Brighton, is an advertisement.

An "Ex High Sheriff, Deputy Lieutenant, and a Magistrate for two Counties," who complains that we have omitted, in a certain instance, to give him his proper designation of Esquire, ought at least to have paid the postage of this important communication.

We shall be glad to receive the calculation Mr. Hall speaks of in his last.

Communications received from Mr. SaulR. C. jun. Mr. Ross-Otto-T. P. W.-Mr. Bayley-Mr. Cooper.

Published by THOMAS KELLY, 17, Paternoster Row; to whom Communications (post paid) for the Editor are to be addressed.

Printed by G. Duckworth, 76, Fleet-street.

Mechanics Magazine,

MUSEUM, REGISTER, JOURNAL, AND GAZETTE.

No. 306.]

SATURDAY, JUNE 20, 1829.

[Price 3d.

"One great and kindling thought from a retired and obscure man, may live when thrones are fallen, and the memory of those who filled them obliterated; and, like an undying fire, may illuminate and quicken all future generations."CHANNING.

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290

HOWARD'S RAILWAY CARRIAGE.

HOWARD'S RAILWAY CARRIAGE. The railway carriage represented in the prefixed engravings is the subject of an American patent, granted last November to Mr. William Howard, of Baltimore, civil engineer; and for the materials of the present account of it we are indebted to the "Journal of the Franklin Institute" (formerly the "American Mechanics' Magazine"), the Editor of which, Dr. Jones, has recently been most deservedly promoted to the superintendence of the Patent Office at Washington.

Mr. Howard states that he had two ends in view in the construction of this carriage. 1st. To render more useful the establishment of a railroad through a broken country, by constructing the carriage so that it should move with as much facility upon a serpentine or curved as on a straight road; while at the same time it should possess all the advantages peculiar to the common method of fixing the wheels on the axis. 2d. To lessen the amount of friction, by arrangements not too complex for general use.

The means (or "principles," as Mr. H. calls them), by which these ends are accomplished, are as follow:

"1st. The connexion of the two beds of the axles at a point equidistant from each; and in the same manner, the connexion between the hind bed of one waggon, and the fore bed of that following it, or the fore bed of the leading waggon with any system of guide wheels, so that the wheels, not only of one waggon, but of a train, will follow one ano. ther in the same curve, without more lateral friction than when on a straight line.

"2d. The making the axle revolve in its journals, and at the same time rendering either one or both wheels capable of revolving, independent of the axle, as in a common carriage.

"3d. The application of a simple friction wheel, to diminish the friction of the axle on its journal."

The following more particular

explanations of these means are given by the patentee:

"1st. If there be a track of a railroad of a circular form, and we wish a carriage to move on it without lateral friction, the planes of the wheels must be parallel to the tangents of the two circles at the points where they rest on them, and each axle, consequently, in the direction of the radius of the circle. To find the point at which the axles must be connected, to produce this effect, draw a perpendicular from the middle of each, and the intersection of these two perpendicular lines will be the point of junction required. The advantage of this over the common construction is, that there the pivot of the beam connecting the axles is on the foremost axle, and, consequently, in turning, the hind wheels do not follow the tracks of the foremost ones, but describe a curve of smaller radius, causing great lateral friction on the rails.

"2d. The principle of making the wheels revolve with or without the axles, in the present case, is to secure the advantages of the axle generally revolving with the wheels, and at the same time to permit one wheel to revolve faster than its fellow, when moving on a curved part of the road. The trifling relative movement which this would produce between the axle and the wheel, would admit of these being adapted with considerable exact

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ON MUSIC, AND TEMPERAMENT SCALES.

tween the fore and bind axles is fastened firmly thereto by jaws or frames, to prevent lateral motion. This beam is divided in the centre, between the axles; one end having a tooth, and the other a socket, of the epicycloidal form, to keep the point of action at an equal distance from the centres of each axle. The axles are kept together by fastening the body, by bolts, to the beds resting upon each. Another method of construction is, to extend the beam from the hind axle, until the end of it rests upon the bed of the fore axle, while the beam from the fore axle reaches to a short distance only behind the central point of action. A bolt then passed through the centre of the hind frame and the end of the fore frame, and equidistant from the axles, forms the pivot, or point of action between them. In this case, the waggon is fastened firmly to the hind bed only, and to the extremity of the hind beam, which rests on the fore bed, which is made to traverse, laterally, more easily, by a small roller upon a curved strip of iron.

"The friction wheels are contained between upright stands, or supports, of cast or wrought iron,—each wheel having one on each side, connected at the top by a bolt and nuts, and having jaws at the bottom, wide enough to admit the axle in contact with the friction wheel; each pair of friction wheels is connected by iron bars passing through each arm of the jaws of the supports, and secured by nuts; between these bars the axle revolves; and the bars rising above the axle receive the beam, and form the fore and hind beds to which the frames of the beam are securely nutted. To obviate the little friction which may arise from the centre of the friction wheel being directly above the centre of the axle, it may be placed a little obliquely, and a small friction roller used in one of the arms of the jaws, to destroy the additional friction there.

"The axles have two shoulders at each end; one of which supports the waggon wheel, and is either firmly fixed to it, or only secured by a

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linch-pin; and the other revolves upon the friction wheel."

Description of the Engravings. Fig. 1 is a perspective representation of the whole carriage.

showing particularly the manner in Fig. 2 is a plan of the waggon, which the beds of the two axles are connected. A is the iron waggon wheel, made as usual, except that it is arranged so as to turn on the axle, to which it is secured by the liuch-pin B, or any other contrivance. C is a wheel fixed upon the axle, as in the the friction wheels, moving upon the common railroad carriage. D D axles E E, and supported by the supports F F. The whole of these and the frames are secured together parts are of wrought or cast iron, by screws and nuts, so as to keep them solid, and as shown in the figure. G one of the bars connecting the two frames together, and secured in like manner. H and I are the two frames, by which the two beds are connected by a bolt at the point K, equidistant from the centre of each axletree; the frame I of the bind bed is prolonged, and rests on part of the frame H, immediately over the fore axle,-the motion of its end, laterally, being facilitated by a small roller at L.

If it be not found objectionable to place the body of the waggon entirely above the wheels, the two friction wheels on one bed may be placed on a common axle. This arrangement will simplify the number of the parts, and contribute to the steadiness of the motion.

ON MUSIC, AND TEMPERAMENT
SCALES.

Sir,-Perhaps it may be amusing to some of your juvenile readers to receive a few scattered hints upon he theory of music.

A chord in music is the unison of three or more sounds which harmonize, and whose vibrations are admeasurable by the primes 1, 2, 3, 5, and their compounds or products.

The number of vibrations of any interval (or note) being given, the

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ON MUSIC, AND TEMPERAMENT SCALES.

vibrations of an interval of the same denomination one octave higher, will be double that number; and every succeeding octave will be in a duplicate geometric ratio to the last.

Schol.-If any sound forming a part of a chord be placed out of the first septave, its vibrations are admeasurable by the primes which measured its octave below.

Cor.-All chords are reducible within a septave; consequently, the denominative of a chord placed out of the septave, in which its fundamental note lies, must be the same as if reduced within that compass. Put a for the number of vibrations made in a given time by the lowest, or fundamental note, of a supposed

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chord of any tone or semitone; for example, we will take the thirteenth. The whole chord will then stand 4 x which

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3a, and 3a, is the

a chord continually used by every composer. The following are scales of temperament I had drawn out some years ago:

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Being provided with a sliding rule divided into any of the above numbers, i. e. 1000, 360, 3010, or 612, the corresponding numbers for 3d, 5th, &c. will appear at sight. Or if the circumference of a circle be divided into any of the above numbers, having a concentric moveable circle, a convenient instrument will be formed for examining all temperaments of that scale.

The interval or difference between the minor tone 10: 9, and the major 98, is as 81: 80; which is termed comma.

This interval is not employed in practical music, but must be distinctly understood by theorists, and particularly in treating of temperament. There are, therefore, four

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descriptions of simple intervals: i. e. intervals which do not include more than a major tone-these are comma, of which the ratio is 81: 80; hemitone, or 16:15; minor tone, or 10: 9; and major tone, or 9:8.

A scale of the inside size and height of every pipe for an organ of five octaves may be conveniently traced on a piece of board six feet long and five inches wide, papered on one side. Thus, first mark off 3 inches for the distance up to the windhole, the size of the smallest

Not having at hand the usual musical signs, the sharps in the above Table are denoted by asterisks (*), and the flats by the letter b.-Printer.

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