of the path of the pulleys, one side of which endless thread takes a single turn round one of the pulleys, and the other side of the thread a single turn around the other pulley, the endless thread being turned by one of the riggers, or by a power applied in any other manner, will draw the pulleys with the same proportional velocity, in the direction of the thread passing around the smaller pulley; see fig. 5, where a is the endless thread, the riggers, e the pulleys, d the lower radius, e the continuing place of the fulcrum of the leverage.

Fig. 5.

"In Mr. Saxton's model at the National Gallery of Practical Science, Adelaide-street, West Strand, the pulleys are about as 8 to 9, consequently the sum 17 to the difference 1, expresses the real velocity of the carriage relative to that of the drawing cord; and a horse at his most effective speed of two and a half miles per hour, attached to an endless rope passing round pulleys in those proportions, would draw a carriage attached to the common axis at the rate of 42 miles per hour."

Now taking Mr. Saxton's elevation (or that of Mr. Hawkins'), viz., that of Shooter's-hill, which is assumed to be the highest at which any rail-road would be of practical utility, and which rises in the ratio of one in eight, I find, by calculation and experiment, that it requires twelve times the power of propulsion at that acclivity, that would suffice upon level ground.

Whatever it is be it what it maythat a single horse power can propel upon a level rail-road, the same weight would require twenty-five horse-power to propel upon Mr. Saxton's plan. Now, it is obvious that, if this be the fact, it would require twelve times twenty-five, or 300

horse-power, to propel any given weight at the above elevation. In order to be distinctly understood upon this point, I will re-state it in other words:-What one horse will perform upon a level rail-road, 300 horses will be required to do upon a plane at the elevation of Shooter's-hill, on Mr. Saxton's plan. How, it may be asked is this immense power to be attained, or, if attained, at what cost? Could any benefit result from it? In my opinion there could not. It follows, then, upon an ascent equal to that of Shooter's-hill, the "locomotive differential pulley" loses all its supposed virtue, and becomes worse than abortive: for, be it remembered, that Mr. Saxton's plan is chiefly recommended upon the ground that it will supersede the necessity of cutting through hills.

It is my object to show, that Mr. Saxton's plan is founded in ignorance of the principles of mechanics. The interest, as well as the honour, of science renders this exposition necessary; but I have no personal feeling whatever in the ques

tion.

An

My model represents a double railroad, the inner one being for the truck (which I shall describe presently), and the outer one for the vehicle to be propelled. The former, as well as the latter, runs upon four wheels. The dif ferential pulley consists of one larger and one smaller pulley fixed together, and both revolving on the same axis. endless rope, that is to say, a rope like a lathe-band, having no termination, passes over the larger pulley of the truck, and thence runs to its destination, viz., the point at which the truck stops; at that point it passes over a fixed pulley; after which, returning, it passes over the second, or smaller pulley of the truck; and, finally, again revolves over the first fixed pulley from which the truck commences its progress. To the rope we have been describing is attached a branch rope, which is fastened to a horse that draws the truck, in the same manner as barges are drawn on the banks of canals. Mr. Saxton proposes that the horse shall go three miles an hour-the vehicle to be propelled in that time thirty miles.

The vehicle to be propelled is placed over the truck, which has a balancecatch in front; this catch strikes against a bar fixed to the vehicle, and the force

of the concussion propels the latter forward. The operation here described is repeated, from point to point, by means of successive trucks stationed at fixed distances froin each other, along the whole line of road to be traversed.

In my model the weight of the vehicle to be propelled is twenty-three ounces and a half, loaded with one hundred and twelve ounces, which make the whole weight equal to one hundred and thirtyfive ounces and a half. This, on a common level rail-road, is propelled by two ounces. Now, by fixing my model in proportion to the elevation of Shooter'shill, I find it requires twenty-four ounces to propel the above weight at that ascent. But, according to Mr. Saxton's plan, the weight of the truck is to be taken into account, viz., twelve ounces, making the total one hundred and forty-seven ounces and a half; and this additional weight renders it necessary to have a power of fifty ounces to be able to propel both truck and vehicle on a common level rail-road. Multiply 50 by 12, and it gives 600 ounces to propel the truck and vehicle at the elevation of Shooter's-hill. In other words, it would take 600 horses to perform, at that elevation, the work of two upon a common level rail-road. In less elevations the power required will, of course, be in proportion. It is, therefore, manifest that the "locomotive differential pulley" can never be made to answer the expectations of the inventor and patrons of the scheme.

But the fundamental objection to the principle of Mr. Saxton's invention is the immense friction it creates; the whole action consists of nothing but friction; whereas every mechanic knows, or ought to know, that the great object should be to diminish friction. The only effect produced, in point of fact, is friction; and, in this respect, the invention reminds me of what Mr. Bramah once denominated a friction machine."

Having trespassed at so much length upon your valuable time, I will only, in conclusion, observe, that I have no wish to exalt myself by depreciating the abilities of others, or to decry any invention calculated to be beneficial to the community; but, in the present instance, being convinced of the futility of the scheme in question, and that it is utterly impracticable for any useful purposes, I think it a duty to disabuse the minds of

IMPORTANT DISCOVERY IN MAGNETOELECTRICITY-DIFFERENTIAL CRANE.

Sir,-Since my last communication I have been engrossed by a course of electro-magnetic and magneto-electric experiments, which have, I am happy to say, ended in a discovery which arms the inquirer into magneto-electricity with power scarcely dreamt of. The details of the discovery, and of the leading and collateral experiments, I have sent, as matter purely scientific, to Professor Jameson's Edinburgh Philosophical Journal, in the April Number, of which they will, if not too late, appear. Should they not so appear, I shall have great pleasure in communicating to you some of the leading particulars; as I am sure many of your readers are interested in the subject, and would feel farther delay a grievance. I may here state so much as that, instead of moving either armature or magnet in developing the magneto-electricity, I keep both stationary; that the motion is confined to a separate auxiliary piece of apparatus to be called a galvanic reverser; that the armature and magnet are of one solid piece, forming together a new instrument, to be called the magneto-electric ring; and, lastly, that the power and capability of enlargement possessed by the apparatus, seem to have scarcely any limit. I can hardly state more at present, without encroaching on matter sent to another journal; and I could scarce do even so much, had not a friend, in whose favour I was keeping the secret, given me to understand that he cannot immediately follow up what I had communicated to him on the subject. I beg to add here, as it may be of use at some future time to have done so, that the first idea was conceived on the 25th of January last, the leading experiments made on the 29th of the same month, and that the first magneto-electric ring, with its auxiliary the galvanic reverser, was completed, aud proved to answer even beyond expectation, on the 22d of Feb. last y

same, and I extract it not only to furnish an additional example of the coincidence of different and independent thinkers in the same train of discovery, but also as a hint worthy, perhaps, of adoption in practice. The coincidence I have alluded to has ceased to surprise me, since I have reflected upon the general uniformity of the structure of the human mind, the limited number and the simplicity of the original models nature places before us, the slight diversity of the materials we have to work upon, and the sameness of the wants and necessities which serve to stimulate to exertion.

EFFECT OF COMBINATIONS ON THE INTRODUCTION AND AMPROVEMENT OF MACHINERY.*

As hostility to machinery is a very prevalent feeling among the working classes, it might be supposed that they would turn all the power of their Unions towards its suppression. In this attempt, however, they have been singularly unsuccessful; and so far have they been from attaining, or even approaching the attainment of this object, that their efforts have led to an exactly contrary result, and some of the most valuable and ingenious machines that our manufac tories can boast of, actually owe their existence to the operation of Trades' Unions.

The cotton trade affords one remarkable instance of the truth of this observation. The evils inflicted on this manufacture by strikes have been detailed; many years ago, the masters with the view of escaping these disastrous effects of the tyranny of the Spinners' Union, requested the machine-makers to attempt the construction of a self-acting mule, that is, of a mule, which should perform its work without the assistance of a spinner. For a long time the attempt was regarded as hopeless, difficulties stood in the way, which it is not easy to describe, requiring, however, all the resources of mechanical genius to surmount. But the suc cessive efforts of mechanists have by degrees overcome every obstacle, and the skill of Mr. Roberts, an eminent machine-maker at Manchester, has brought the invention to perfection. The most extraordinary power of this machine, consists in its manner of re gulating the motion of the spindles, when the mule is receding to its frame; during this retrograde course, which carries the mule over the space of 44 feet, about three times a minute, the velocity of the spindles is constantly changing, and this continues as many hours as they are filling with thread; they exhibit, to speak mathemati cally, a Auxion of movement; during no two successive portions of time, however small, is the speed the same. The machine may now be seen in action in several mills, and almost appears to to realise the finest results, that could be expected from human ingenuity.

The following evidence taken by the

Committee of Manufactures and Commerce, which sat last Session, will show the way in which the combination of the spinners is forcing the adoption of this machine. It is given by Mr. Graham, a Scotch manufacturer:

"We are paying much higher in Glasgow than they are paying in England for spinning the same numbers, and in consequence of this, we have been driven to employ machines, which may supersede those men (spinners).

"Are you aware of any cotton-spinning work, where the proprietors are turning out the old machinery in consequence of the combination of the workmen, and introducing self-acting mules? We are doing it ourselves.

66

Have you adopted the self-acting mule to get rid of combinations?-Before adopting the self acting mule, I had the plans drawn, and I called a deputation from the men in, and explained it to them, and I said, You drive us either to take machines, or you drive us to bankruptcy, or to stop our works; here is an order going off to Manchester for self-acting mules; we do not wish to introduce them, and we will be the last house to introduce them, if you will take the same wages that they have in Lancashire; and they said, It is no use, we are determined not to reduce our wages.''

The introduction of this invention will eventually give a death-blow to the Spinners' Union, the members of which will have to thank themselves alone, for the creation of this destined agent of their extinction. It is now rapidly coming into use ; other advantages, besides the great one of escape from the dietation of the workmen, are found to attend it; and in a few years the very name of working-spinner, as well as the follies and oppression of their combination, will only be found in history.

The turn-out of the Lancashire workmen in the building-trade, has introduced a curious application of the steam-engine. This machine is now employed in some towns, instead of manual labour, in hoisting the various building-materials to the top of the edifice, where they are intended to be used. The magnificent design of the Liverpool custom house is at the present moment rising into existence by the assistance of steam. The following letter from a masterbuilder, who was one of the principal sufferers in this strike, graphically describes the circumstances attending the introduction of the improvements

"Sir, I have much pleasure in complying with your request, and shall feel happy if any information, which I can affords will be useful to your purpose) About two years ago, the bricklayers? labourers, whom I had

at work at the new custom-house here, began to exhibit symptoms of rebellion, the building being unusually large, and requiring much work I found that, just in proportron as we were hurried, the labourers began to relax and grow careless, and sometimes did not do a sufficient quantity of work to cover their own wages. My wits were accordingly set to work to discover a remedy. I well knew that if I resorted to severe measures, a general strike would have been the consequence; but as we had on the ground, about 35 yards from the front of the edifice, a 7-horse steam-engine for the purpose of mixing up our lime and sand into mortar and making grout, I had the shaft of the mill lengthened, and a drum fixed upon it; attached to this was a chain governed by a break, which we carried in a hollow trough under ground, and connected with a crossbeam placed upon two uprights on the top of the building. We then placed 300 bricks in a square box, slung it, and tried our engine. The bricks went up in fine style, and were received at the top by waggons placed Ton a light railway, furnished with crossslides, and the result was that two labourers could fill the boxes with bricks below, sling them on the chain, and two more receive them at the top, who, by the help of the Yailway conveyed them (weighing 23 cwt.) to any part of the building with ease. We thus rendered useless the services of about 20 hod-carriers at once, at the cost of about 100%. in machinery. The remainder of the men were for a long period quiet, and would have continued so, had not the Trades' Unions virtually compelled them to strike, many of them against their wills. The contrivance just mentioned has acted so well, that, when in full work, we usually send to the top of the building 16,000 bricks per diem, with 7 or 8 tons of mortar and grout, the engine all the while doing its other accustomed work. This would only pay in large buildings; in small erections the expense of fixing the machinery would be too great; but small high-pressure steam-engines are now made, which stand upon 3 feet square, consume about 1 cwt. of coal a-day, and will hoist with sufficient rapidity 25 ewt. to any height, they are also sufficiently portable to be moved about in small earts; or I am satisfied that a horse with a rope and pulley, working through a snatch-block, would be cheaper and better than the old system of manual labour. SATUTA Kİ,

The contractor for the stone-work at the new custom-house raises all his materials by a small engine(I think it is 18-horse power, which cost him 150 and his other additional machinerydabout 2007. more, sile sends his stonès (varying from toulstons Badweight)" up to the summit> with perfect

ease. His engine like ours is stationary, and his ropes run'round the building to that part where the work is proceeding, and though they are sometimes 500 feet in length, no difficulty is experienced from this cause. We send up indiscriminately, bricks, stone, iron, or timber; the engine is much more tractable and civil than the hod-men, easier managed, keeps good hours, drinks no whiskey, and is never tired. I need hardly add that in a large building it is much cheaper, more expeditious and satisfactory, than carrying up materials on men's shoulders. The time consumed by the men in de scending, and by the slowness of their ascent consequent on the loss of strength caused by having to overcome the gravity of their own bodies, before they have strength to spare for carrying a heavy burden, makes the hod-carriers far inferior to the steamengine, more especially if we consider the constancy with which the latter works. I do not now fear a turn-out of hod-carriers, because I have proved that we can do very well without them, and I think that I now see many other modes of saving labour, which I should instantly avail myself of, were another strike to happen amongst my workmen. It is also obvious to myself that many of the uses to which machinery is now applied, may be traced to turn-outs, which, having subjected masters to inconveniences, have compelled them to scheme mechanical contrivances, that otherwise would not have been thought of. Feeling that improve. ments in mechanism will not eventually injure the labourer, yet I would not hastily adopt such, as would suddenly deprive a number of men of their subsistence, did not their own folly compel me to it. I am now quite sure that another strike or two will annihilate many hod-carriers, and brickmakers, and this principle of hoisting by stationary or moveable steam-engines, will, no doubt, be adopted for many other pur. poses, if the operatives in particular departments endeavour to force their employers to pay a higher rate of wages than they can afford. For instance, we know that two stationary engines at each dock, with shafts and drums running along the quays, would discharge the cargoes of all the ships, with a tenth of the porters now employed; at present I should be sorry to see it adopted, but I know before long it must be done.

Iam, Sir,

"Your very faithful servant,
"SAMUEL HOLME."

Liverpool, Feb. 7, 1834."