GALLOWAY'S FATENT PADDLE-WHEEL. Sir, Mr. Galloway in the construction of his wheel has assumed that the paddles will form a cycloidal curve in their passage through the water, and an advantage thus be gained by each rib of the float-boards following in the wake of the other. Were the water at rest, (neither flowing with the vessel nor against it), and the vessel travelling at the same speed as that at which the wheels revolve, then the cycloidal curve might be produced; but even that is an assumption which wants proof. Mr. Galloway has only taken into account the vessel's motion, and that erroneously calculated as equal to the velocity of the wheels, and has left the tide (either for or against) out of the question; and I can assure Mr. Galloway it will tarry for no man-not even for him nor for his wheels.

The inventor seems also to have overlooked the consideration, that a square inch, forming a part of a small surface, will not offer resistance equal to that of a square inch forming part of a larger surface; the property of fluid bodies being, that when one particle is struck, that particle strikes another, and another until some way of escape is found from the propelling or striking body. Therefore, a body of water will possess in a greater degree the nature of a solid resisting medium when struck with a certain, compact superficies, than when struck with same total, but divided, surface. This effect is, of course, in proportion to the distance between the portions of the total surface and the size of each of these portions. Mr Galloway, by dividing the paddle into bars or slips, therefore makes avenues for the esc pe of that which for the propulsion of the vessel it is an object to take hold of. It may be answered, that this law of fluids has not time to come into operation in consequence of the velocity of the wheel; but if this be the case, then is the new wheel worse than useless, in consequence of the immense back-water it would produce; because in such case the cycloidal paddles would act like so many buckets, each upon its emersion listing a quantity of water according to its dimensions, the velocity not giving time for any escape between the interstices, and throwing it out when the

cycloidal curved buckets become re versed; and perhaps not then, for it is not impossible that the wheel might at tain a velocity equal to that of a glass of water which a conjuror will swing round without spilling a drop!

Taking this view of the matter, the wheel would be more efficient revolved in a contrary way; such, indeed, was what I thought was intended to be the case on a first glance at the engraving, and before noticing the directing-arrow or reading the description. A naval friend of mine, well acquainted with the subject, also, upon looking at another engraving of the wheel without any directingarrow, and judging of the action merely from the drawing or plan, gave it as his opinion, that it was intended to turn in the direction which it appears would be backward.

Suppose Mr. Galloway's wheel to be effective in all the particulars which he claims, what is to be done in the backing of a vessel? From the shape and disposition of the paddles, they cannot ing; and if it has not the power of backbe equally effective both ways of revolving pretty quickly, it will be of little use in a river so crowded with craft as the Thames. In the course of navigating the pool, how often are the commands of the captain or pilot to the engineer -"back her!" "stop her!" uttered for the purpose of avoiding collision with large, or the running down of small vessels? From my own observation, I should say some twenty or thirty times in the course of a trip to Gravesend. Alas! for wherries, boats, and barges, when the adoption of Mr. Galloway's invention shall put it out of the engineer's power suddenly to stop and back the steamer by reversing the wheel's rotation !

Yours, &c.
SCRUTATOR MECHANICUS.

Dec. 28, 1835.

RAILWAY THEOREMS.

Sir, I am sorry to see the pages of your useful Magazine occupied by erro neous theorems intended to elucidate well-understood subjects.

gravity generates equal velocities in It is very generally known, that equal times, or, in other words, that a heavy body left to the free action of

gravity, has, at the end of one second, attained a velocity of 32 feet per second, at the end of 2 seconds 64 feet per second, and, to state it generally, at the end of n+1 seconds the velocity is 32 feet per second greater than it was at the end of n seconds.

It is also familiar to all persons who attend to these things, that if a body at rest be suffered to descend freely down an inclined plane, whose height is 16 feet, it will, when it arrives at the end of such plane, have acquired a velocity in the direction of the plane of 32 feet per second, let the length of the plane be what it may. And if it has a velocity of m feet per second when it begins to descend the inclined plane, it will have a velocity of m+32 feet per second at the end of it. Hence the theorem, v=V+gt sin. i.-See Gregory's "Mathematics for Practical Men," page 238, first edition.

In the above, friction and its effects are disregarded; and the fractions are rejected.

Dec. 28, 1835.

66

Yours, &c.

S. Y.

P.S.-Allow me to ask Iver M'Iver what every writer on the subject" means s and h, to represent in the equation, he has given page 251.

NOTES AND NOTICES.

The First Amendment of a Specification, under the late Patent Law Amendment Act was only enrolled a few days ago. We shall give the particulars in our next. There was a certain Special Attorney, it may be remembered, who asserted that as inuch had been done as far back as the 5th of October last (with the view of showing that we knew nothing of the matter), and who afterwards gave the Clerk of the Clerk of the Clerk of the Patents as his authority, which Clerk of the Clerk of the Clerk of the Patents never publicly denied that the falsehood had been traced back to its proper source. We leave both gentlemen to their own reflections.

Palladium has not until within the last few years been an object of attention from its great scarcity, the ore of platina being the only source from which this metal was derived, and in which Dr. Wottas. ton first discovered it in 1803. I noticed the existence of palladium in the Brazilian gold, in the year 1812, Philosophical Magazine, vol 1x., but until my engaging with the Imperial Brazilian Mining Company, its extraction to any extent in a state of purity, and for use in the arts, had not been effected. Palladium exists in the gold of the Gongo Socodistrict, partly in a native state, and partly in combination with the gold. It is separated by the nitric acid with the silver used for refining, and with which it was formerly collected. The properties of this metal render it intrinsically valuable in the arts, having most of the characters of platina,

which it also resembles in colour. It is not corroded by the action of the atmosphere-is not af fected by acids (except the nitric), under extraor dinary circumstances-is perfectly malleable, and being only 11 specific gravity, has an advantage over platina in its introduction. It is being exten. sively used in mathematical instruments, taking very fine gradations, also by dentists in lieu of gold or platina, for lightning points, scale-pans, small weights, points of pencils, in lieu of steel, and a great variety of other purposes. Its alloy with other metals are also highly interesting-it hardens silver, and prevents it from tarnishing, for which property it might be advantageously introduced in surgical instruments,-with copper and iron it has the elasticity of the best steel. The oxide of palladium is used by enamellers for forming a fine hair brown colour.-Mr.O.N.Johnson, Mining Journal,

LIST OF SCOTCH PATENTS GRANTED BETWEEN THE 21ST NOVEMBER AND 18TH DECEMBER, 1835, INCLUSIVE.

John Reynolds, of Liverpool, gentleman, for improvements in railways. Sealed at Edinburgh, December 7, 1835.

Samuel Faulkner, of Manchester, cotton-spinner, for an improvement in the carding of cotton and other fibrous substances, by a new application of the machinery now in use for carding cotton or other fibrous substances. December 9.

Miles Berry, of No. 66, Chancery-lane, London, in consequence of a communication made to him by a foreigner residing abroad, for an improvement or improvements in the making or construct. ing of meters or apparatus for measuring gas, water, and other fluids. December 9.

John Houldsworth, of Glasgow, cotton-spinner, in consequence of a communication made to him by a foreigner residing abroad, for certain im. provements applicable to drawing and slubbing frames used in the manufacture of cotton and other fibrous substances. December 18.

Patents taken out with economy and despatch; Specifications prepared or revised; Ca. veats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice..

Mr. R. Coles-Answered by post.

We are much obliged to Mr. Dixon for his suggestion, and shall do our best to open "the sealed book."

Communications received from Mr. ClibborneMr. Crombie-Mr. March-Antiquus-R. R.-Mr. Chittenden-C. L. P.-T. C.-Mr. Matthews - Mr. Waldron.

Erratum.- Page 252, first column, line 24, for "turned" read " tinned."

The Supplement to the last volume, containing title, index, &c. and portrait of Charles Vignoles, Esq., C. E., is just published, price 6d. Also, the volume complete, in boards, price 9s. 6d.

LONDON: Published by J. CUNNINGHAM, at the Mechanics Magazine Office, No. 6, Peterbo rough-court, between 135 and 136, Fleet-street. Agent for the American Edition, Mr. O. RICH, 12, Red Lion-square. Sold by G. G. BENNIS, 55, Rue Neuve, Saint Angustin, Paris. CUNNINGHAM and SALMON, Printers, Fleet-street..

HUTCHISON'S PATENT PORTABLE LEVER.

The portable lever represented by the prefixed drawing, consists of a square thread screw, a, three inches in diameter and nine feet in height, placed in a perpendicular position, at one extremity of a light and portable carriage g. Immediately in the rear, and within four inches of the screw, there is a cast-iron standard b, connected at its lower extremity with the bearing stand i, upon which the screw rests; within two feet of the top of this standard projects a collar or stay c for the purpose of steadying and causing the screw a to act with the necessary precision. A moveable cast-iron lever or arm d projects horizontally from the screw a. This lever rests upon a copper box e, the interior of which is a female screw. The principal action of the machine takes place when the two screws, viz. that in the box and the nine feet, are put in motion by the turning of the cross-head f. D is an oblique inclination of the lever, which presses upon the standard b, by means of the roller E; and this roller travelling up and down with freedom upon the back part of the standard, renders perfectly secure and accurate the entire action of the lever, The standard and screw attached to a revolving axle at i, so that, by disengaging the bolts which secure the strutts m m, the whole apparatus may be lowered upon the stage g. This process is so exceedingly simple, that it may be effected with perfect ease in less than five minutes. N is a slight and removable platform, which rests upon the strutts m m, and is chiefly supported by the brackets o o. Upon this platform, the person who works the cross-head stands. The fore part of the carriage rests upon a swivel axle z, for the purpose of enabling the machine to pass with facility any obstructions which may be in its way. The travelling roller E may be placed near the standard at P. By this simple contrivance the lever is raised from its horizontal position to such an angle or elevation, as will suit the nature of the work it is required to perform.

are

It will be perceived, upon an accurate inspection of this machine, that it possesses several important advantages.

The facility with which it may be conveyed, wherever its services are re

quired, is of itself a very strong recommendation.

To most of the machines which are employed in raising ponderous weights, a catch or lock is necessary to prevent the too rapid descent or falling of the article suspended by the rope or chain. But by the action of the portable lever, the article raised or lowered is always secure from the accident of slipping: it is therefore unnecessary for the man employed in turning the cross-head to adopt any precaution for the purpose of preventing such an occurrence.

Accidents are daily taking place through the breaking of a chain, the snapping of a rope, or the sudden illness of the person employed in turning the windlasses of cranes, and other machines usually employed in lifting heavy materials. But this lever is not liable to any of those disarrangements which result from such casualties.

This useful machine was constructed under the direction of Mr. Hutchison, expressly for raising, placing, and withdrawing the retorts in the London Gas Works at Vauxhall; and these various processes are now executed by means of it with the utmost precision, combined with a most important saving of time and materials.

A tolerably correct estimate of its value may be formed, when it is stated that it executes in fifteen minutes the entire day's work of twelve men. It is calculated that the saving to the London Company, where there are nearly 1,100 retorts in action, effected by this contrivance of their ingenious engineer, has, in the space of eight months, amounted to 400l.

There can be little doubt, therefore, of its being adopted at all similar establishments.

We understand that, in consequence of the peculiar applicability of this lever to lifting and placing heavy pieces of ordnance, &c., it is in contemplation to adopt it in his Majesty's dock-yards..

STREET-PAVEMENTS.

Sir,-In one of your late numbers,

C. B. says, "Mr. Davy's remark that

certain destruction awaits the knees of horses falling down upon the rugged surface of the new coach-pavement in Cow-lane, Fish-street-hill, &c., is true

to a certain extent; but so long as the new pavement is kept in a good working state (as rough as when first pitched I presume is meant), there is scarcely any fear of a fall, except in descending !"

Why, Mr. Editor, no one, whether riding or driving, dreads falling when going up hill.

Once more let me be heard through your columns in this matter.

My simple proposition, offered to the public in various ways more than eight years ago, was to pitch the streets with granite, rough on the edges or sides, three to four inches broad each way, of the same dimensions at the bottom as on the surface, and on no account to taper the stones more than where required.

By-the-bye, the wiseacre improvements of cutting by the chisel the large blocks, and now of setting the stones at an angle, prove that the city officials, who are always looking more to the money things will bring to their own pockets, than to the advantage of the public (for example, that infamous job Farringdon Market), were indebted to my suggestion for these modifications and again, let me din in their ears, "that it is the interstices between the paving-stones which ensures the safe foot-hold of the horse in his progress, whether slow or quick.”

;

And farther, that the size of the paving-stones laterally, is of as much consequence as their being shortened in the transverse or cross breadth (three to four inches each way is the full dimension); for every one knows that horses often slip sideways, as well as straightforward. These small stones

with the openings between them, would render a paved road as safe, or safer, than a macadamised one, and less expensive, too, than the present heavy blocks; for the pieces of sufficient depth (fourteen or fifteen inches) might be triangular, square, nearly circular, or of any shape, as chance might furnish them, if all rough, in some degree, on three sides, of an equal depth."

In short, this method I so long ago proposed, would approach, as near as can be, to the macadamised road, without its liability to wear out, and its occasional inequalities when new, and when worn down.

I cannot omit this opportunity of once

more urging on the public the value of a railroad on the banks of the Thames, from Westminster to London Bridge, for passengers in steam carriages. The countless accidents occasioned by those. insolent fellows, cab and omnibus drivers, together with the confusion and delay in passing to and fro from one end of this Babylon to the other, loudly call for prevention in some shape or other Allow me to refer to one of your former numbers for some of the details of my project, and to express a hope that some one, who has more time and money to spare than I have, will start the thing, and feel the pulse of the public thereon.

Dec. 30, 1835.

T. C.

MR. HERAPATH'S RAILWAY THEOREMS.

Sir, The concluding remark I made in my article (p. 219) was, "That Mr. Herapath had done himself great injustice by denying that his theorems for railway transit were not intended to be mathematically true." Let the reader contrast this remark with what Mr. Herapath states at the beginning of No. 2 of his series" Were I (says Mr. Herapath) to pursue the course most agreeable to myself, and which might perhaps be expected of me, I should begin with a mathematical investigation of the theory of railroads, &c." The only part of Mr. Herapath's investigations that can be called mathematical is given at the beginning of No. 3 of his series, viz. arti, cle 1, on the force of traction on an ascending or descending plane, the force of traction being 9lbs. per ton on a level.

h

The expressions, "11 very nearly,"

22

h ; but when h22, then friction and gravity balance one another; and when h is greater than 22, there cannot be an equilibrium between friction and gravity, unless we suppose that steam or some other force is employed in opposition to gravity. Also when the plane ascends,