Chapter 6

The next great improvement of Watt, in addition to the condenser, is the air-pump, the use and absolute necessity for which you will understand when I explain its action. Watt first used it for his atmospheric engine. The piston of this engine was kept tight by a flow of oil and water on the top, which tended to make the whole a troublesome and bad-working machine. The cold atmosphere, as the piston went down, of course followed it and cooled the cylinder. On the piston again rising, some steam would of course be condensed and cause waste. If the engine-room could be kept at the heat of boiling water, this would not have been the case, but the engineman who could live in this heat would also require to be invented, and so this had to be given up. Watt's next and most important step was the one which brings us to talk of the steam-engine as it now is in the present day. This important step was the idea, of making the steam draw down the piston, as well as help to drive it up; in the first engines it was raised by the beam, and steam used only to cause a vacuum, so as to let the air drive it down. All before this had been merely steps in advance, like those of children, who must walk before they can run; so was it with the steam-engine. It was uphill work for many years, and the top of the hill cannot be said to have been readied till Watt worked out this grand idea. The first engine could only be called atmospheric; now it was destined to become in reality a steam-engine. Time would fail were I to attempt to go into any details of all the experiments through which Watt toiled to bring his ideas to perfection--enough to say that he did so; and I trust you will be able, through the description I will endeavour to give, to understand how well his labour was bestowed, and how beautiful the result has proved for the benefit of the world at large. In 1773, Watt removed to Soho, near Birmingham, where a part of the works was allotted to him to erect the machinery necessary to carry out his inventions on a grand scale.

We must now proceed to some of the useful points of the engine, all I have before mentioned simply relating to the inventors and improvers; but having brought it so far, I may now, I think, proceed further. The first use of the steam-engine was simply to raise water from mines, and for long it was thought it could be used for nothing else; so much so, that it was at one time used to raise water to turn wheels and thus produce motion. One of its first uses after it became a really useful machine was to propel ships, though many a weary hour was spent to bring it to this point. There is a very pretty monument on the Clyde, dedicated to Mr. Bell, who I believe was the first person who successfully brought steamers to work on its waters. The first who used steam for ships was Mr. James Taylor, in conjunction with Mr. Miller of Dalswinton. The danger of the fire-ship took such hold on people's minds that it was with great toil and difficulty they were persuaded to venture on the face of the waters in such dangerous and unseamanlike craft. But go to Glasgow Bridge any day, and you will see how time has overcome fear and prejudice, for our ocean is covered with steamers of all sizes. It is not many years ago since it was said that steamers could never reach America; this has given way to proof, and even Australia has been reached by steam. I know of a steamer building which could carry the whole population of this place and not be full; she is 680 feet or 226 yards long, and a large vessel would hang like a boat alongside her.

The first attempt at giving motion by steam to ships was of course only in one way--by a ratchet at the end of a beam, at one moment driving and the next standing still. This was on account of the engine being only in power one half of the stroke; but by the double-acting engine being introduced, and the steam acting both ways, it became at last a steady mover (without the aid of two or three cylinders, as in the first engines, one to take up the other as the power was given off), by a ratchet on the end of a beam or else a chain. This acted on the shaft which moved the paddles. It is to Watt that we are indebted for the crank and direct action, so as to give a circular motion to the wheels.

We find in 1752 a Mr. Champion of Bristol applied the atmospheric engine to raise water to drive a number of wheels for working machinery in a brasswork, in other words, a foundry. Also, in Colebrokedale, steam-engines were used to raise water that had passed over the wheel, so as to save water. All these plans have, however, now passed by, like the water over the wheel, and we now have the engine the prime mover--the double action of the steam on the piston, this acting on the sway beam, and the beam on the crank, which, by the assistance of the fly-wheel on land or fixed engines, gives a uniform motion to the machine. All these have now enabled us to apply the engine as our grand moving power. One great and important point in the engine is the governor, and the first modes of changing the steam from the top to the bottom of the cylinder were cumbrous, till the excentric wheel was devised.

Boilers also have to be attended to--these were at first rude and now would be useless. They were unprovided with valves, gauge-cocks, or any other safety, all of which are now so well understood that nothing but carelessness can cause a blow-up. One of the greatest causes of danger is that of letting there be too little water in the boiler, and thus allowing it to get red-hot, when, if you let in water, such a volume of steam is generated that no valve will let it escape fast enough. Force or feed pumps are also required to keep the water in the boiler at a proper height, which is ascertained by the gauge-cocks. Mercury gauges for low pressure act according to the pressure of the atmosphere; high-pressure boilers of course require a different construction, as the steam is greater in pressure than the air.

Having got so far in my subject, I think before concluding I must devote a short time in showing the first steps of the locomotive; the more so, as I am speaking to those who are so largely engaged in the daily working of that now beautifully perfect machine. Various and for a time unsuccessful experiments were made to bring out a machinery or travelling engine, as it was first called. A patent was taken by a Mr. Trevethick for a locomotive to run on common roads, and to a certain extent it did work. An amusing anecdote is told of it. In coming up to a toll-gate, the gatekeeper, almost frightened out of his seven senses, opened the gate wide for the monster, as he thought, and on being asked what was to pay, said "Na-na-na-na!" "What have we got to pay?" was again asked. "No-noth-nothing to pay, my dear Mr. Devil; do drive on as fast as you can!" This, one of the first steam carriages, reached London in safety, and was exhibited in the square where the large station of the London and North-Western Railway now stands. Sir Humphrey Davy took great interest in it, and, in writing to a friend, said: "I shall hope soon to see English roads the haunts of Captain Trevethick's dragons." The badness of roads, however, prevented its coming into general use.

Trevethick in 1804 constructed a locomotive for the Merthyr and Tydvil Rail in South Wales, which succeeded in drawing ten tons at five miles an hour. The boiler was of cast-iron, with a one-cylinder engine, spur gear and a fly-wheel on one side. He sent the waste steam into the chimney, and by this means was very nearly arriving at the blast-pipe, afterwards the great and important discovery of George Stephenson. The jumping motion on the bad roads, however, caused it constantly to be dismounted, and it was given up as a practical failure, being sent to work a large pump at a mine. Trevethick was satisfied with a few experiments, and then gave it up for what he thought more profitable speculations, and no further advances were made in locomotives for some years. An imaginary difficulty seems to have been among the obstacles to its progress. This was the supposition that if a heavy weight were to be drawn, the grip or bite of the wheels would not be sufficient, but that they would turn round and leave the engines stationary, hence Trevethick made his wheels with cogs, which of course tended to cause great jolts, as well as being destructive to the cast-iron rails.

A Mr. Blenkinsop of Leeds patented in 1811 a locomotive with a racked or toothed rail. It was supported on four wheels, but they did not drive the engine; its two cylinders were connected to one wheel behind, which was toothed and worked in the cog-rail, and so drove the engine. It began running on Middleton Coal Rail to Leeds, three and a quarter miles, on the 12th August 1812, and continued a great curiosity to strangers for some years. In 1816 the Grand Duke Nicholas of Russia saw this engine working with great interest and expressions of no slight admiration. An engine then took thirty coal-waggons at three and a quarter miles in an hour.

We next come to Messrs. Chapman of Newcastle, who in 1812 tried to overcome the supposed want of adhesion by a chain fixed at the ends of the line and wound round a grooved drum driven by the engine. It was tried on the Heaton Rail near Newcastle, but was found to be so clumsy that it was soon abandoned. The next was a remarkable contrivance--a mechanical traveller to go on legs. It never got beyond its experimental state, and unfortunately blew up, killing several people. All these plans show how lively an interest was then being taken in endeavouring to bring out a good working locomotive. Mr. Blackett, however, persevered hard to perfect a railway system, and to work it by locomotives. The Wylam waggon-way, one of the oldest in the North, was made of wooden rails down to 1807, and went to the shipping-place for coals on the Tyne. Each chaldron-waggon was originally drawn by a horse with a man in charge, only making two journeys in the one day and three on the following, the man being allowed sevenpence for each journey. This primitive railway passed before the cottage where George Stephenson was born, and was consequently one of the first sights his infant eyes beheld; and little did his parents think what their child was destined to work out in his day for the advancement of railways. Mr. Blackett took up the wood and laid an iron plate-way in 1808, and in 1812 he ordered an engine on Trevetbick's principle. It was a very awkward one, had only one cylinder of six inches diameter, with a fly-wheel; the boiler was cast-iron, and was described by the man who had charge of it as having lots of pumps, cog-wheels, and plugs. It was placed on a wooden frame with four wheels, and had a barrel of water on another carriage to serve as a tender. It was at last got on the road, but would not move an inch, and her driver says:--"She flew all to pieces, and it was the biggest wonder we were not all blown up." Mr. Blackett persevered, and had another engine, which did its work much better, though it often broke down, till at length the workmen declared it a perfect plague. A good story is told of this engine by a traveller, who, not knowing of its existence, said, after an encounter with the Newcastle monster working its great piston, like a huge arm, up and down, and throwing out smoke and fire, that he had just "encountered a terrible deevil on the Hight Street road."

We now come to George Stephenson, who did for the locomotive what Watt did for our other steam-engines. His first engine had two vertical cylinders of eight inches diameter and two-feet stroke, working by cross-heads; the power was given off by spur-wheels; it had no springs, consequently it jolted very much on the then bad railways; the wheels were all smooth, as Stephenson was sure the adhesion would be sufficient. It began work on the 25th July 1814, went up a gradient of one in 450, and took eight waggons with 30 tons at four miles an hour. It was by far the most successful engine that had yet been made. The next and most valuable improvement of Stephenson was the blast-pipe--by its means the slow combustion of the fire was at once overcome, and steam obtained to any amount. This pipe was the result of careful observation and great thought. His next engine had horizontal connecting rods, and was the type of the present perfect machine. This truly great man did not rest here, but time would fail, as well as your patience, if I were to proceed further. Enough to say, that he afterwards established a manufactory at Newcastle, and time has shown the result and benefit it has proved to the whole world at large. A short time before the Liverpool and Manchester Railway was opened, Stephenson was laughed at because he said he thought he could go thirty miles an hour, and was urged before the House of Commons not to say so, as he might be thought to be mad. This I have from person who knew the circumstances. Nevertheless, at the trial, I believe the "Rocket" did go at the rate of thirty miles an hour, to the not small astonishment of the world, and especially to the unbelievers in steam as a land agent. The stipulation made was that trains were to be conveyed at the rate of twelve miles an hour.

In our present perfect engines, the coke or fuel consumed per mile is about 18 lbs. with a train of 100 tons gross weight, carrying 250 passengers. A first-class carriage weighs 6 tons 10 cwts.; a second-class, 5 tons 10 cwts., each with passengers; a Pullman car weighs about 30 tons. Our steamers consume 5 lbs. of coal per horse-power in one hour. And last, not least, one of the greatest improvements we have had in steam propulsion is the screw. Again, I may also name the great advantage derived from steam by our farmers in thrashing out grain. The engines principally used in farm-work are what are termed high-pressure, or of the same class as the locomotive. The great saving in cost in the first place, the simplicity and ease of action in the second, and the small quantity of water required to keep them in action, are all reasons why they should be preferred. The danger in the one, that is, the high-pressure, over the condenser, is very small, and all that is required is common care to guard against accidents. Steam being a steady power, is much to be preferred to water, as by its constant and uniform action the tear and wear of machinery is much diminished, and of course proportionate saving made in keeping up the mill or any other machinery.

Having now, to the best of my power, so far as a single lecture will permit, brought the steam-engine from 120 B.C. to the present time, it only remains for me to say, that it shows how actively the mind of man has been permitted to work to bring it to perfection by the direction of an all-wise Providence, "who knows our necessities before we ask, and our ignorance in asking." A traveller by rail sees but little of the vast and difficult character of the works over which he is carried with such ease and comfort. Time is his great object. No age of the world has conquered such difficulties as our engineers have had to deal with, and the result is now before the eye of every thinking traveller. Our engineers were at first self-taught, and many a self-taught man has had reason to rejoice in the time he spent in his education. Of these men we have examples in Brindley, who was at first a labourer and afterwards a millwright; Telford was a stone-mason; Rennie a farmer's son apprenticed to a millwright; and George Stephenson was a brakesman at a colliery. Perseverance with genius, and a determination to overcome, made them the great men they were. That you may so persevere and strive is the earnest wish of him who has this evening had the great pleasure of giving you this lecture, and who feels so greatly obliged to you for the very patient hearing you have given him.

_ON ATTRACTION_.[B]

_Gravitation_.--Attraction, which may be illustrated by the effect a magnet has on a piece of iron, may be viewed generally as an influence which two bodies, say, exert on each other, under which, though at a distance, they tend to move towards each other till they come into contact. The force by which a body has weight, and, when free, falls to the ground, is of this nature; and it is called, from _gravis_, "heavy," the gravitating force of the earth, because it causes weight, and because, though emanating in a small degree from the falling body, it is mainly exerted by the earth itself. It is under the action of gravity that a pendulum oscillates: it is by that unseen influence it begins to sway alternately downward and upward as soon as it is moved to a side; and it is only because it is withheld by the rod that the ball or bob keeps traversing the arc of a circle and does not fall straight to the earth.

All material substances, however small, and however light, buoyant, and ethereal they may seem, are subject to this force: the tiniest speck in a sunbeam and the most volatile vapour, equally with the heaviest metal and the hugest block, the particles of bodies as well as the bodies themselves. The rising of a balloon in the air may seem an exception to this law; but it is not so; for the balloon rises, not because the particles of the gas with which it is inflated are not acted upon by the earth's attraction, but because the air outside being bulk for bulk heavier than the air inside, its particles press in below the balloon and buoy it up, until it reaches a stratum of the atmosphere where, the pressure being less, the air outside is no heavier than the air within--a fact which rather proves than disproves the universal action of gravitation; because the greater weight of the air in the lower strata of the atmosphere is due to the pressure of the air in those above, and the balloon ceases to ascend because it has reached a point where the air outside is the same weight as the air within, and the weight in both cases is caused by the attraction of the earth.

And not only is the force of attraction universal, it is the same for every particle; for though this may seem to be contradicted by the fact that some bodies fall faster to the ground than others, that fact is fully accounted for by the greater resistance which the air offers to the falling of lighter bodies than to the falling of heavier. A particles of bodies, and all bodies, tend to fall with the same velocity, and, in fact, all do; for though, for the reason just stated, a feather will take longer to reach the ground than an ounce of lead, an ounce of lead will fall as fast as a hundredweight. And that it is the resistance of the air, and not any diminution in the power of attraction, which causes the feather to lag behind, may be proved by experiment; for if you let a feather and a coin drop together from the top of the exhausted receiver of an air-pump, they will both be seen to descend at the same rate, and reach the bottom at the same instant; a fact which may be demonstrated more simply by placing the coin and feather free of each other in a paper cone, and letting the cone fall with its apex downwards, so as to break the air's resistance; or by suspending a piece of gold-leaf in a bottle, and letting the bottle drop--of course short of the ground--in which case the included leaf will be seen to have gone as fast and as far as the bottle.

It is to be especially noticed that attraction is no lopsided affair; that it is mutual; that, while the larger body attracts the less, the less also attracts and moves the larger in proportion; and that, indeed, every body and every particle attracts every other, far as well as near, to the utmost verge of the universe of matter. Under it the moon maintains its place with reference to the earth, the planets with reference to the sun, and the solar system with reference to the stellar. As for the moon, it maintains its orbit and revolves round the earth under the action of two forces, the one akin to that by which a ball is projected from the mouth of a cannon, and the other the attraction of the earth, which, by its constant and equal operation, bends its otherwise rectilineal track into a circular one, as we might show if we could only project a ball with such a force as exactly to balance the power of gravity, so that it would at no point in its course be drawn nearer the earth than at starting.

That the force we are considering pervades the solar system is demonstrable, for it is on the supposition of it and the laws it is known to obey that all the calculations of astronomy--and they never miscarry--are grounded; and it is by noticing disturbances in the otherwise regular movements of certain planets that astronomers have been led more than once to infer and discover the presence of some hitherto unknown body in the neighbourhood. It was actually thus the planet Neptune was discovered in 1846. Certain irregularities had been observed in the movements of Uranus, which could not be accounted for by the influence of any other bodies known to be near it; and these irregularities, being carefully watched and studied, gradually led more than one astronomer first to the whereabouts, and then to the vision of the disturbing planet.

Notwithstanding what we said about the universality of this force, and how it affects all forms of matter, it may still appear as if the air were an exception. But it is not so; the air also gravitates. The fact that it gravitates is proved in various ways. First, if it did not, it would not accompany the earth in its movements round the sun; the earth would sweep along into space, and leave it behind it. Secondly, if we place a bottle from which the air is exhausted in a balance and exactly poise it with a counter-weight, and then open it and let in the air, it will show at once that the air has weight or gravitates by immediately descending. Thirdly, if we extend a piece of india-rubber over the end of a vessel and begin to withdraw the air from it, we shall see the india-rubber sink in, under the pressure of the air outside, to fill up the space left vacant by the removal of the included air. The fact that air gravitates we have already taken for granted in explaining the ascent of a balloon; and the proofs now given are enough to show that the cause assumed is a real one. The lighter gas rises and the heavier sinks by law of gravitation.

_Gravitation and Cohesion._--Unlike the attraction of aggregation, or cohesion, which acts only between particles separated from each other by spaces that are imperceptible, gravitation takes effect at distances which transcend conception, but it diminishes in force as the distance increases. The law according to which it does so is expressed thus; its intensity decreases with the square of the distance; that is to say, at twice the original distance it is 1-4th; at thrice, 1-9th; at four times, 1-16th, for 4, 9, 16 are the squares respectively of 2, 3, and 4. To take an instance, a ball which weighs 144 lb. at the surface of the earth will weigh 1-4th of that, or 36 lb., when it is twice as far from the centre as it is at the surface; and 1-9th, or 16 lb. when it is thrice as far; and 1-16th, or 9 lb. when it is four times as far. The attraction of cohesion, on the other hand, as we say, acts only when the particles seem almost in contact, and it ceases altogether when once, by mechanical or other means, the bond is broken, in consequence of the particles being forced too near, or sundered too far from, one another.