Part 9

Davy was an eloquent, enthusiastic, forceful speaker. He prepared his lectures with the greatest care, and he delivered them with that attention to dramatic effect which is instinctive in all really great speakers. Coleridge said, “I attend Davy’s lectures to increase my stock of metaphors,” and there were many others who went to hear the young chemist for other reasons than a liking for science. He had his own theories of the arts of public address. “Great powers,” said he, “have never been exerted independent of strong feelings. The rapid arrangement of ideas from their various analogies to the equally rapid comparisons of these analogies, with facts uniformly occurring during the progress of discovery, have existed only in those minds where the agency of strong and various motives is perceived--of motives modifying each other, mingling with each other, and producing that fever of emotion which is the joy of existence and the consciousness of life.”

In addition to his lectures Davy worked hard in the well-stocked laboratory of the Institution, where he was supplied with a corps of capable assistants. His researches covered a very large part of the field of chemistry, and he was indefatigable in running down any new idea which his active brain chanced to hit upon. In his vacations from London he went to the farthest regions of the British Isles, spending considerable time in the north of Ireland and the Hebrides. Here he studied the geological structures, and collected all the information he could in regard to agriculture. Anything to do with natural science interested him. He sketched a great deal, and he was forever asking questions of all the countrymen he met. His questions made him famous in many a hamlet, where such inquisitiveness had never been known before.

Shortly after he had moved to London he had been asked to investigate astringent plants in connection with tanning. To this end he visited tan-yards and farmers, and in 1802 began to deliver a course of lectures on “The Connection of Chemistry with Vegetable Physiology.” These lectures proved remarkably popular, and for ten years he repeated them at the meetings of the Board of Agriculture. They were later published in book form, and so great was their interest that they were translated into almost every European language. _The Edinburgh Review_, that dean of British critics, said, “We feel grateful for his having thus suspended for a time the labors of original investigation, in order to apply the principles and discoveries of his favorite science to the illustration and improvement of an art which, above all others, ministers to the wants and comforts of man.”

When his agricultural researches were finished he went back to his studies with the voltaic pile or battery. He discovered that potash and soda can be decomposed, with the resultant metals of potassium and sodium. When he made this discovery he was so delighted that he danced about the room, and was too excited to finish the experiment for some time.

He had worked too hard, and soon after this discovery he fell ill. For days all London watched for the bulletins of the young chemist’s condition. Fortunately he recovered, and in time went back to the work which was proving so invaluable for the world of science.

The Royal Institution now provided him with a voltaic battery that was four times as powerful as any that had previously been constructed. With this he made numberless chemical discoveries. The Royal Society had made him a fellow when he was twenty-five years old, and one of its secretaries when he was twenty-nine. His London lectures grew continually more popular. The Dublin Society invited him to lecture in that city, and his course at once attracted the greatest attention. He was already the scientific lion of England, but withal a very modest and unassuming lion. Cuvier said, “Davy, not yet thirty-two, in the opinion of all who could judge of such labors, held the first rank among the chemists of this or of any other age.” The National Institute of France awarded him the prize that had been established by Napoleon for the greatest discovery made by means of galvanism. Then, in 1812, when he was thirty-three, he was knighted by the Prince Regent.

Sir Humphrey Davy, as he now was, married Mrs. Appreece, a woman of many talents and unusual intelligence. She was rich, and soon after their marriage Davy was able to resign his professorship at the Royal Institution, which he had held for twelve years, and devote himself to original research and to travel. Carrying a portable chemical apparatus for his studies, Sir Humphrey and Lady Davy went first to Scotland, and then to France, Italy, and Germany. They met the most prominent men of the age in those countries. These men found the famous chemist interested in everything about him, as much of a poet as a scientist. In Rome he wrote a sonnet to the sculptor Canova, and the literary circles of Italy proclaimed him a poet after their own heart.

Davy was now one of the foremost chemists of the world, but he could as yet hardly lay claim to the title of inventor. He had been an ambitious man, and had once said that he had escaped the temptations that lay in wait for many men because of “an active mind, a deep ideal feeling of good, and a look toward future greatness.” That future greatness had always been in his thoughts, and had been one of the compelling powers in his great chemical discoveries. But beyond this thought of greatness was a very deep and earnest desire to help his fellow men. So when the chance to do this offered he took advantage of it at once.

Explosions of coal-gas were only too common in the mines of England. They were almost always fatal to the miners, and formed the greatest peril of those who labored underground. In 1812 a terrible explosion occurred in a leading English mine, and caused the death of almost a hundred miners. The mine had caught on fire, and had to be closed at the mouth, which meant certain destruction to those within. The catastrophe was so great that the biggest mine-owners met to see whether some protection against such accidents could not be devised. After much discussion they appointed a committee to call on Sir Humphrey Davy and ask him to investigate the possibilities for them.

Davy realized that here lay his opportunity to be of real service to men, the goal he had always had in mind. He took up the question, experimented with fire-damp, and found that it was in reality light carburetted hydrogen. He visited many mines, and took into careful consideration the conditions under which the men worked. For months he investigated and experimented, and at length, in 1815, he constructed what he called the safety-lamp. This was an oil lamp which had a chimney or cage of wire gauze. The gauze held the flame of the lamp from passing through and igniting the fire-damp outside. It was only possible for a very little of the fire-damp to penetrate the gauze and such as did was held harmless prisoner. The cage allowed air to pass and light to escape, and although by the combustion of the fire-damp the wire gauze might become red hot, it was still efficient as a safety-lamp.

Davy’s safety-lamp proved exactly what was needed to act as protection from exploding fire-damp. It was tried under all conditions and served admirably. George Stephenson had worked out a somewhat similar safety-lamp at about the same time, and his was used in the collieries around Newcastle. In the rest of England Davy’s lamp was at once adopted. All miners were equipped with either the Davy lamp or the “Geordie” lamp, as the other was called, and the mine fatalities from fire-damp immediately decreased. This lamp is still the main safeguard of those who have to contend with dangerous explosive gases in mines all over the world.

Friends urged Davy to patent his lamp, and thus ensure himself a very considerable income from its sale. But he said, “I never thought of such a thing: my sole object was to serve the cause of humanity; and if I have succeeded, I am amply rewarded in the gratifying reflection of having done so. I have enough for all my views and purposes; more wealth could not increase either my fame or my happiness. It might undoubtedly enable me to put four horses to my carriage; but what would it avail me to have it said that Sir Humphrey drives his carriage and four?”

His fellow men appreciated the great value of this service he had rendered. At Newcastle, the centre of the mining country, a dinner was given in his honor, and a service of plate, worth over twelve thousand dollars, was presented to him. The Emperor of Russia sent him a magnificent silver-gilt vase, with a letter congratulating him on his great achievement, and the King of England made him a baronet.

Davy himself, in spite of his reputation as a chemist, placed this invention above all his other work. “I value it more than anything I ever did,” said he. “It was the result of a great deal of investigation and labor; but if my directions be attended to, it will save the lives of thousands of poor men. I was never more affected than by a written address which I received from the working colliers when I was in the north, thanking me on behalf of themselves and their families for the preservation of their lives.”

Davy’s note-books are most interesting reading and show the philosophic trend of his thoughts. At one time he said, “Whoever wishes to enjoy peace, and is gifted with great talents, must labor for posterity. In doing this he enjoys all the pleasures of intellectual labor, and all the desire arising from protracted hope. He feels no envy nor jealousy; his mark is too far distant to be seen by short-sighted malevolence, and therefore it is never aimed at.... To raise a chestnut on the mountain, or a palm in the plain, which may afford shade, shelter, and fruit for generations yet unborn, and which, if they have once fixed their roots, require no culture, is better than to raise annual flowers in a garden, which must be watered daily, and in which a cold wind may chill or too ardent a sunshine may dry.... The best faculties of man are employed for futurity: speaking is better than acting, writing is better than speaking.”

He was fond of travel, and after he had seen the successful use of his lamp he went abroad again. When he returned he was made president of the Royal Society, a position which had been made illustrious by Sir Isaac Newton. The British navy asked him to discover what could be done to prevent the corrosion of copper sheathing on vessels, caused by salt water. He made experiments, and at last succeeded in rendering the copper negatively electrical by the use of small pieces of tin, zinc, or iron nails. But shells and seaweed would adhere to the non-corroded surface, and hence the process was not entirely successful. This principle of galvanic protection, however, was found to be applicable to many other purposes.

These and other experiments in chemistry and electricity, travel, and his duties as president of the Royal Society filled his days. In 1826 he was attacked by paralysis, and from then he spent much of his time on the continent, seeking health and strength. He wrote on fishing and on travel, and all his writings, on whatever theme he touched, are filled with the love of nature and of beauty, and permeated with that philosophic balance that had been characteristic of his whole career. He died in Geneva, May 29, 1829.

Davy was not the born inventor, drawn irresistibly to construct something new. He was the born chemist, and it was only when he was asked to investigate the nature of the fire-damp that he fell to studying whether some adequate protection could not be afforded the miners. Yet he himself said that he was more proud of his safety-lamp than of all his other discoveries, and although the scientists and chemists may think of Humphrey Davy as a great experimenter, great lecturer, and great writer on chemistry and electricity, the world at large knows him best for his safety-lamp and for the great change for the better he was able to bring about in the mines of England.

IX

STEPHENSON AND THE LOCOMOTIVE

1781-1848

The need of finding a new way of working the coal mines of England, and of marketing the coal, which had been such an important factor in the development of the steam-engine, was a scarcely less important factor in the building of the earliest practical railway locomotive. The coal had to be hauled from the pit of the colliery to the shipping place. It was carried in cars that were pushed or pulled over a rude line of wooden or iron rails. But it was evident from the time when James Watt began to build his steam-engines to lift the coal from the mine that men of inventive minds would soon seek to send the cars over the level ground by the same power. We owe the railroad chiefly to the needs of the north of England, and there we find the real birth of the locomotive.

About the beginning of the nineteenth century a number of men in England were experimenting with new means of locomotion, both for merchandise and for passengers. Their projects varied from cars running on wheels and drawn by horses to carriages propelled by small stationary steam-engines, placed at short distances from each other along the road. In 1802 Richard Trevethick, a captain in a Cornish tin-mine, took out a patent for a steam-carriage. The machine he built looked like an ordinary stage-coach on four wheels. It had one horizontal cylinder, which was placed in the rear of the hind axle, together with the boiler and the furnace-box. The motion of the piston was carried to a separate crank-axle, and that in turn gave the motion to the axle of the driving-wheel. This was in itself a great invention, being the first really successful high-pressure engine that was built on the principle of moving a piston by the elasticity of steam against only the pressure of the air. The steam was admitted from the boiler under the piston that moved in a cylinder, and forced it upward. When the motion had reached its limit, the communication between the piston and the under side of the cylinder was shut off, and the steam escaped into the atmosphere. Then a passage was opened between the boiler and the upper end of the piston, which was consequently pushed downward, and then the steam was again allowed to escape. As a result the power of the engine was equal to the difference between the atmosphere’s pressure and the elastic force of the steam in the boiler.

This steam-carriage of Trevethick was fairly successful, and created a great sensation in that part of Cornwall where it was built. He decided to take it to London, and drove it himself to Plymouth, from which port it was to be carried by sea. On the road it caused amazement and consternation, and won the name of Captain Trevethick’s dragon. He exhibited it in London, but after a short time gave up driving it, believing that the roads of England were too badly built to make the use of a steam-carriage feasible.

Other men were working on similar lines. Among them was the owner of a colliery in the north named Blackett, who built a number of engines for propelling coal-cars and used them at his mines. But these were very clumsy and heavy, moved slowly, and had to be continually repaired at considerable expense, so that other miners, after examining Blackett’s engines, decided they were not worth the cost of manufacture. To make the steam-carriage really serviceable it must be more efficient and reliable.

Meantime a young man named George Stephenson, who was working at a coal mine at Killingworth, seven miles north of Newcastle, was studying out a new plan of locomotive. His father had been a fireman in a colliery at Wylam, a village near Newcastle, and there the son George was born on June 9, 1781. He had lived the life of the other boys of the village, had been a herd-boy to care for a neighbor’s cows, had been a “picker” in the colliery, and separated stones and dross from the coal, had risen to assistant fireman, then fireman, then engineman. He was strong and vigorous, fond of outdoor sports, and also considerable of a student. In time he moved to Willington Quay, a village on the River Tyne, where coal was shipped to London. Here he married, and made his home in a small cottage near the quay. He was in charge of a fixed engine on Willington Ballast Hill that drew the trains of laden coal-cars up the incline.

After he had worked for three years at Willington he was induced to take the position of brakesman of the engine at the West Moor Colliery at Killingworth. He had only been settled in his new place a short time when his wife died, leaving him with a son Robert. Stephenson thenceforth threw himself into his work harder than ever, studying with his son as the boy grew older, and spending a great deal of time over his plans for a steam-engine that should move the coal-cars. He knew the needs of the colliery perfectly, had acquired a good knowledge of mechanics, and proposed to put his knowledge to account.

He had already, as engine-wright of the Killingworth Colliery, applied the surplus power of a pumping steam-engine to the work of drawing coal from the deeper workings of the mine, thereby saving a great amount of manual and horse labor. When the coal was drawn up it had to be transported to the quays along the Tyne, and to simplify this Stephenson laid down inclined planes so that a train of full wagons moving down the incline was able to draw up another train of empty wagons. But this would only work over a short distance, and was in itself a small saving in effort.

The engines that Mr. Blackett had built, using Trevethick’s model as a basis, were working daily near the Killingworth Colliery, and Stephenson frequently went over to see them. He studied Mr. Blackett’s latest locomotive, nicknamed “Black Billy,” with the greatest care, and then told his friend Jonathan Foster that he was convinced that he could build a better engine than Trevethick’s, one that would work more effectively and cheaply and draw a train of cars more steadily.

He also had the advantage of seeing other primitive locomotives that were being tried at different places near Newcastle. One of these, known as Blenkinsop’s Leeds engine, ran on a tramway, and would draw sixteen wagons with a weight of seventy tons at the rate of about three miles an hour. But the Blenkinsop engine was found to be very unsteady, and tore up the tram-rails, and when its boiler blew up the owner decided that the engine was not worth the cost of repair. Stephenson, however, drew some useful points from it, as well as from each of the other models he saw, and proposed to himself to follow Watt’s example in constructing his steam-engine, namely, to combine the plans and discoveries of other inventors in a machine of his own, and so achieve a more complete success.

Stephenson was now very well regarded at the colliery for the improvements he had made there. He brought the matter of building a new “Traveling Engine,” as he called it, to the attention of the lessees of the mine in 1813. Lord Ravensworth, the principal partner, formed a favorable opinion of Stephenson’s plans, and agreed to supply him with the funds necessary to build a locomotive.

With his support Stephenson went to work to choose his tools and workmen. He had to devise and make many of the tools he needed, and to train his men specially for this business. He built his first engine in the workshops at the West Moor Mine. It followed to some extent the model of Blenkinsop’s engine. It had a cylindrical boiler, eight feet long and thirty-four inches in diameter, with an internal flue tube passing through it. The engine had two vertical cylinders and worked the propelling gear with cross-heads and connecting-rods. The power of the two cylinders was carried by means of spur-wheels, which continued the motive power to the wheels that supported the engine on the rails. The engine was simply mounted on a wooden frame that was supported on four wheels. These wheels were smooth, as Stephenson was convinced that smooth wheels would run properly on an edge-rail.

This engine, christened the “Blutcher,” and taking about ten months to build, was tried on the Killingworth Railway on July 25, 1814. It proved to be the most successful working engine that had yet been built, and would pull eight loaded wagons of about thirty tons’ weight up a slight grade at the rate of four miles an hour. For some time it was used daily at the colliery.

But the “Blutcher” was after all a very clumsy machine. The engine had no springs, and its movement was a series of jolts, that injured the rails and shook the machinery apart. The important parts of the machinery were huddled together, and caused friction, and the cog-wheels soon became badly worn. Moreover the engine moved scarcely faster than a horse’s walk, and the expense of running it was very little less than the cost of horse-power. Stephenson saw that he must in some way increase the power of his engine if he was to provide a new motive power for the mines.

In this first engine the steam had been allowed to escape into the air with a loud, hissing noise, which frightened horses and cattle, and was generally regarded as a nuisance. Stephenson thought that if he could carry this steam, after it had done its work in the cylinders, into the chimney by means of a small pipe, and allow it to escape in a vertical direction, its velocity would be added to the smoke from the fire, or the rising current of air in the chimney, and would in that way increase the draught, and as a result the intensity of combustion in the furnace. He tried this experiment, and found his conjecture correct; the blast stimulated combustion, consequently the capability of the boiler to generate steam was greatly increased, and the power of the engine increased in the same proportion. No extra weight was added to the machine. The invention of this steam blast was almost the turning point in the history of the locomotive. Without it the engine would have been too clumsy and slow for practical use, but with it the greatest possibilities of use appeared.

Encouraged by the success of his steam blast Stephenson started to build a second locomotive. In this he planned an entire change in mechanical construction, his principal objects being the use of as few parts as possible, and the most direct possible application of power to the wheels. He took out a patent for this engine on February 28, 1815. This locomotive had two vertical cylinders that communicated directly with each pair of the four wheels that supported the engine, by means of a cross-head and a pair of connecting-rods. “Ball and socket” joints were used to make the union between the ends of the cross-heads where they united with the connecting-rods, and between the rods and the crank-pins attached to each driving-wheel. The mechanical skill of his workmen was not equal to the forging of all the necessary parts as Stephenson had devised them, and he was obliged to make use of substitutes which did not always work smoothly, but he finally succeeded in completing a locomotive which was a vast improvement on all earlier ones, and that was notable for the simple and direct communication between the cylinders and the wheels, and the added power gained by using the waste steam in the steam blast. This second locomotive of Stephenson’s was in the main the model for all those built for a considerable time.