fect in the form of models and drawings, turn out useless in the attempt to bring them into action, proceeded to the subject of Balancing. The position which he was prepared to maintain at the outset of this part of his subject was the following:-There is not among machinists sufficient care taken to construct all revolving machinery as nearly as possible in balance. This would appear in a more striking point of view to be of importance, when it was seen, as he was now prepared by models to prove, that inattention to balancing diminished according to a certain function of velocity, the power; and originated, in the second place, so much destructive, dangerous, and at all times disagreeable rocking and agitation in machinery. And, first, deficient balancing produced diminution of power. Here Dr. M. described the crank, and particularly the double crank, with its connecting rod-stating its use in converting an alternate rising and falling motion into a rotary one, as in the locomotive engine, and vice versa. He now took into his hand a model of a locomotive crankshaft, and showed how difficult it was to make it revolve above once or twice with the greatest force he could exert upon it by his fingers. This done, he took up one exactly similar, but having a counterpoise to each crank, and by the same force it performed with ease several revolutions. The lecturer next ran a rod of brass into the head of a running capstan, and having placed the brass rod so as to project equally on each side of the head, caused it to revolve by means of a six-pound weight; it continued to revolve for 46 seconds, and performed in the time 241 revolutions, as read off on a counter. He next put the rod all out on one side, and all other things being equal, the rod revolved only 30 seconds, and performed only fifty revolutions. These experiments proved the position that inattention to balancing involves a decided loss of power. Experiments were next instituted to show that under these circumstances an increase of power may not only be thrown away, but that such an increase will absolutely tend to diminish the velocity. A three-pound weight caused a model out of balance to revolve longer and perform more revolutions than a six-pound weight. This brought the lec turer to his second position, viz., that deficiency of balancing will create a rocking motion and an agitation of the machinery which will be greater or less as the want of balance is greater or less. It was in the year 1810, whilst Mr. Heaton was employed at Combe Abbey, by the late Earl of Craven, in a part of his lordship's establishment kept for the amusement of himself and his visitors in the practice of mechanical pursuits,

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as turning, sawing by circular saws, ornamenting by the aid of rose engines, &c., the covers of snuff boxes and other fancy articles, that, finding his hand power insufficient, his lordship determined to have a small steam-engine erected of sufficient power to drive the lathe, &c., at the requisite speed. The engine having been put up, his lordship and many of his visitors were surprised to find that when one of the lathes was urged to a speed of about 600 revolutions in the minute it began to shake, and shook to such an extent as the speed was augmented as to raise the whole lathe and frame from the floor upon which it was placed. Mr. Heaton was, of course, consulted as to the cause of this agitation, and he attributed it unhesitatingly to the fact that the revolving parts of the machine, the pulleys, were not equal in weight on both sides of the centre. The lathe was of beautiful workmanship, made by one of the best makers in London, and the pulley suspected of the fault was made of rosewood, on which was fixed a dividing-plate. Now, it was probable that the texture of the wood being closer on one side than on the other when dry, was the cause of this inequality in the weight. Mr. Heaton had immediate instructions to remedy this defect if possible, and he accomplished it in the following manner: -He bored a hole on the light side of the pulley 3 inches from the centre, and introduced into it nine ounces of lead, which was the quantity required to make the pulley perfectly in balance. The lathe was now again set to work, and at a speed of 600 revolutions per minute, or any other speed requisite for its work, it was perfectly free from shaking. This rocking motion was now illustrated on a large model, whose axis was of the breadth of the ordinary railway gauge, and its two revolving rods of the length of the diameter of the wheels of a locomotive engine. Being unequally balanced, and made to revolve by a weight of six pounds, it exemplified the rocking motion of the lathe. The same motion, Dr. M. observed, may also be noticed in some of the guide pulleys that are heavy.sided on the railways, where a rope is used to draw the train along, particularly when the train runs fast. Here several corrections of machinery, both of lighter and more ponderous construction, were severally detailed, in which Mr. Heaton had succeeded, by attention to this principle, in producing an equable motion, where before the most violent and unaccountable agitation had prevailed. One striking instance occurred in the latter part of last year: an application was made to the firm of Heaton Brothers, Shadwell-street, for instructions to remedy

the evil attendant upon the working of a fan used for the purpose of creating a blast for melting iron; this fan had been set to work, but the steam-engine by which it was driven was found incapable of getting it up to the required speed, which was about 1,000 revolutions per minute, and when it approached that speed it shook the whole of the buildings, and shook itself loose from its bearings. To obviate this position of affairs, the proprietors removed it into another position, and propped it with strong timbers, which strong timbers had their bearing under a heavy wall. When again set to work it shook the whole place as before, and made so much noise, that the proprietors were threatened with a prosecution for nuisance. At this critical juncture of affairs, Messrs. Heaton, having been consulted, immediately took the fan to pieces, and found it 2lbs. 8ozs. out of balance. The evil was rectified, and the fan restored to its former position, short of the whole of its props, &c. The engine was now set to work, and was found capable of driving the fan the requisite number of times, the nuisance was removed, and the fan had never since displayed any disposition to move from the place where it was set. Here an important observation was made, to the effect that the outside of the wings of this fan, which was three feet in diameter, when running at 1,000 turns per minute, does not travel quite twice as fast as the rim of the wheels of a railway train when the train is running at the speed of thirty miles an hour. The motion of the fan was now imitated on the large model, in which experiment the weights on the outside of the steel rods were not propelled at the rate of fifteen miles an hour, although the effect was so violent; whilst, at the same time, the weights travelled at a uniform speed in each part of their revolution. This was not the case with the wheels of a railway train; for if a train were travelling at the rate of thirty miles per hour, the top part of the wheels would, of course, have a much greater motion than the centre. If, then, such an effect were produced by the model, when only twelve ounces out of balance, and only moving that twelve ounces at the rate of fifteen miles per hour, what effects were we not prepared to expect from a railway wheel thrown forward at four times the speed, and where, as in many instances was the case, the wheels were each four times that much out of balance. Dr. Melson now exhibited a model of the locomotive crank shaft and wheels, one inch to the foot, and made it revolve; when the revolution of the wheels became rapid, it shook the board upon which it was placed with comparative violence, and rocked

itself from one side of the box upon which the experiment was performed to the other. Next the cranks were counterpoised by weights placed opposite each crank in its nearest wheel, and the same velocity having been communicated to its revolutions, it revolved rapidly without the slightest perceptible agitation. Now, to show that it was not merely the increased momentum in the revolving wheels which gave the model this steadiness, Dr. Melson removed the counterpoises, and substituted larger weights in their place, and the first condition of agitation was produced even more powerfully than before. Similar, and equally convincing experiments were now performed on the large model. To show that these pitching and rocking motions were the identical motions communicated to railway trains, when running at a high velocity, and that the observations he had made were loudly called for by the circumstances attendant upon railway accidents, Dr. Melson now proceeded to give an elaborate series of references to the newspaper accounts of the inquests held on the bodies of the sufferers from the accidents which occurred on the Eastern Counties Railway, June, 1839, and August, 1840; and on the London and Brighton Railway, in October, 1841. From this evidence, it was seen that the rocking motion preceded in every instance the accident; that it was produced by augmented velocity; that the rails were perfect before the accident; that indications of lateral pressure were clear and unquestionable; that there is the same rocking on the Great Western Railway; that the opinions given by the different engineers fell short of the explication of the cause of the accident; and that many were, in short, opinions of little or no value; that there is a great difficulty, after all, in getting at the truth in these cases; and that one of the witnesses, in one case absolutely saw the engine leap up, and alight off the rails. The report of the officers of the railway department for 1842 was next as carefully examined, and it was found that the sentiments of Brunel, Professor Barlow, and Sir F. Smith, as therein embodied, went to confirm the evidence given at the several inquests, and to prove that the causes were yet doubtful which originated the oscillatory and pitching motions that preceded the accidents. The pages of the report particularly referred to were, 70, 71, 72, 76, 145, 194, 195, 203, &c. Immediately after the occurrence of the accident on the London and Brighton Railway, Mr. Heaton addressed to the Times the following letter, which, however, was never printed, and which has never yet been before the public.

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"To the Editor of the Times. Sir,-Seeing in your valuable publication accounts of various accidents on the railways, I find in several instances the accident has been attributed to the engine having acquired a rocking and jumping motion, and, in consequence, running off the rails. To prevent this, some of your correspondents advise the use of six-wheeled engines; such being by them considered safer (but in this I do not agree) than the four-wheeled engines, and not so liable to the rocking and jumping motion. I think the cause of the complaint exists in some of each sort, and as much in six-wheeled engines as in four-wheeled ones; and that cause being the unevenness in weight of some portions of the machinery-(I mean the crank shaft and appendages ;) and considering that any arrangement of machinery that would secure steadiness of motion, and render accidents less frequent, would be of public utility, is my apology for troubling you with this communication.

"In the year 1831, myself and brothers constructed a locomotive engine for the common road. We found, in our first experiment, when we run the engines, (which were of 12 inch stroke only,) at from 160 to 180 strokes per minute, (which, by the arrangement of our machinery we were enabled to do,) the jumping and rocking motion was so great as to preclude the possibility of keeping our seat upon the engine; being aware that this motion could only be produced by some portions of our machinery being out of balance, we placed a compensating weight opposite each crank, and repeated our former experiment upon the same road, and found we attained greater speed with no greater consumption of fuel; and the machine travelled perfectly steady at any speed, and free from any symptoms of rocking or shaking. Knowing that this same evil existed in locomotive engines on railways, I constructed, in the summer of 1838, a model of a crank-shaft and wheels of a locomotive engine, (to a scale of 1 inch to the foot,) and in the month of October, in the same year, I delivered it into the possession of the then resident engineer of the London and Birmingham Railway, at Birmingham; a description of which was published in the Mechanics' Magazine of April, 1839, of which the following is a copy :'Lateral and Oscillating Motion of Locomotive Engines.

---

'Sir, My attention having been drawn to the lateral and shaking motion of engines upon rail. ways, and believing it to be in proportion to the

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weight of the cranks and gearing, and the position in which the outside cranks, if any, are placed, I made a small model of the engine-crank shaft, with two wheels upon it, in the proportion of 1 inch to the foot, which I placed upon two strong upright wires, the wires having been made fast in a piece of board. I attached a weight to a string wrapped round the middle of the crank shaft, for the purpose of giving a certain degree of velocity to the crank and wheels, by falling a certain distance, and then being released, say from the table to the floor. The momentum or speed thus attained was sufficient to keep the crank shaft and wheels in motion seventy-five seconds, and the swing of the cranks produced a lateral and oscillating motion sufficient to cause the model to move, or jump across the table upon which it was placed. I then placed a weight on each wheel sufficient to balance the crank, and with the same weight to give motion, and travelling the same distance as in the first case, gave sufficient momentum to keep the crank shaft and wheels, although heavier than before, ninety seconds, and the model stood steady where it was placed upon the table.

'I submitted my experiments to the engineers of the London and Birmingham Railway, who, in. structed by the directors, ordered one of the company's engines, (the Brockhall, at that time under repair at Mr. Middleton's, the Vulcan Iron Foundry, Birmingham) to have balance weights applied to it, according to my plans, and under my superintendence. The engine, when set to work with balance weights upon the wheels had one uniform steady pull at its work; the side sway was gone; it ran equally steady, whether it made 6 or 160 strokes per minute, which is not the case with railway engines generally, for the greater the speed, the greater the snatching and swinging motion. After the engine had worked seven weeks, and had acquired the reputation of a very steady engine, I, with the consent of the engineers of the railway, removed the balance weights from the wheels, and found the same snatching and swinging motion with this engine as is common to all locomotive engines of the usual construction. I found that the engine, when running at or upwards of twenty-two miles per hour, would advance and recede from and to the tender from three-quarters of an inch to an inch every stroke of the engine, and proved the advantage of the balance on the engine equal to the effect on the model. Persons acquainted with railway locomotives will, from the foregoing statements, readily see the great and many advantages to be derived from so simple and yet so effective an arrangement.-Yours, respectfully,

'GEORGE HEATON. Shadwell-street Mills, Birmingham.'

"Since that time, some of the most celebrated manufacturers of locomotive engines have added to their engines balance weights, fixed in the wheels in so neat a manner as scarcely to be noticed, particularly by persons not much acquainted with this description of machinery. Whether the engine which caused the accident on the Brighton Railway, or the one that made the rails into the form of a snake on the Eastern Counties Railway some time ago, had balance weights or not, I do not know, but from the description of the accidents, as given in your publication at the time, I should say they had not. Why locomotive engines should continue to be made, and used, (and I know

"Weighing one hundred and eighty-four pounds, fixed 22 inches from the centre."

they are,) without paying particular attention to this subject, is a matter of surprise to me, when the cost of the necessary appendages to balance the cranks, connecting rods, &c., would not, in the manufacture of a new engine, exceed forty shillings. Why this important feature in mechanics should be neglected by railway engineers is astonishing, as it must be known to them that it is particularly attended to in all other kinds of machinery; and even by themselves, when turning these same cranks for the locomotive engines in the lathe, at their manufactory, a balanced weight is used to make them run steady during the operation. To further illustrate the necessity of great care in this department of the science of mechanics, I will instance the simple machine used for the purpose of grinding the points of pins: this is composed of two discs or pieces of steel, about 6 inches diameter, and weighing about 12 pounds each; they are fixed upon a thin spindle or shaft, and require to be propelled round at about 3,500 times per minute. These mills or discs are always set out of truth with each other, but require to balance each other so nicely, to determine their resting steady in their journals, that one-twentieth part of an ounce out of balance with each other would render the machine unsafe to the workman, being liable to jump from its bearings, and unfit for use. The outside of the discs (or 'mills,' as they are called by the workmen) travel but little more (if so much at times) than double the speed of the locomotive engines-say 5,250 feet per minute, or nearly sixty miles per hour. The cranks of locomotive engines (with wheels of 5 feet diameter, and stroke of piston 18 inches) travel, when conveying a mail train, at about onesixth, and sometimes at about one-fifth, of the speed of the outside of the pin mill, and are about (including the connecting rods, brasses, cutters, &c.) one hundred and eighty pounds out of balance, and, when the train is going at the rate of thirty miles per hour, has to swing round from 180 to 200 times per minute: these cranks being at right angles, and some distance from the axis of the engine, one on one side and the other on the contrary side of the axis, swinging round at such a pace, is, in my opinion, the cause of the rocking motion. The engine running for some time at one uniform speed, and at a high velocity, the springs are acted upon by the unevenness or swinging of the cranks, connecting rods, &o., until the springs and cranks keep time with each other, when the jumping motion commences, and at every stroke of the engine is increased to a great extent, and if the speed cannot be immediately seriously altered, (which is found im.

possible with a heavy train,) the engine vill, in spite of all other efforts to prevent r jump off the rails.

"Yours respectfully,

"GEORGE HEATON. "Shadwell-street Mills, Birmingham, October 23, 1841."

Dr. Melson concluded by referring to the fact that the compensation principle was already beginning to gain much upon public favour; that on the Birmingham and Manchester (Crewe) Line such engines were universally adopted, and that on several of the lines there were individual engines of this character. The straight-axled engine is decidedly superior to the other, but here the evil obtains, inasmuch as the crank-pins and connecting rods are not compensated.

NEW STEAM FRIGATE THE LARGEST IN THE WORLD.

The Admiralty have given instructions for the building and equipment of a new steam frigate, which is to surpass, in size and power, every thing of the kind yet afloat. She is to be of 650 horses power; to have engine room for 600 tons of fuel; complete stowage under hatches for one thousand troops, with four months' stores and provisions, exclusive of a crew of about four hundred and fifty men; and is to be armed with twenty guns of the heaviest calibre, besides carronades. The Cyclops, Gorgon, Geyser, and other war steamers now talked of as wonders for magnitude, will sink into insignificance as compared with this; the largest of them will be little more than half her size. For the sake of greater expedition she is to be made out of one of the large class frigates lately built (the Penelope, cut into two, with 55 feet in length 44) added. The originator of this plan is John Edye, Esq., the able assistant surveyor of the Navy, (well known to all naval architects for his invaluable work on the "Equipment, Displacement, &c., of Ships, and Vessels of War") and she is to be completed at Chatham Ďockyard, under his immediate superintendence and direction. The engines are to be the Gorgon plan, and the commission for building them has been given to the inventors of that plan, Messrs. John and Samuel Seaward. The vessel is expected to be fully completed, and ready for sea before the close of the present year.

on

The conduct of the Government in