THE greatest benefactor of the human race died more than half a million years ago. He was a hairy creature with a low brow and sunken eyes, a heavy jaw and strong tiger-like teeth. He would not have looked well in a gathering of modern scientists, but they would have honoured him as their master. For he had used a stone to break a nut and a stick to lift up a heavy boulder. He was the inventor of the hammer and the lever, our first tools, and he did more than any human being who came after him to give man his enormous advantage over the other animals with whom he shares this planet.

Ever since, man has tried to make his life easier by the use of a greater number of tools. The first wheel (a round disc made out of an old tree) created as much stir in the communities of 100,000 B.C. as the flying machine did only a few years ago.

In Washington, the story is told of a director of the Patent Office who in the early thirties of the last century suggested that the Patent Office be abolished, because ``everything that possibly could be invented had been invented.'' A similar feeling must have spread through the prehistoric world when the first sail was hoisted on a raft and the people were able to move from place to place without rowing or punting or pulling from the shore.

Indeed one of the most interesting chapters of history is the effort of man to let some one else or something else do his work for him, while he enjoyed his leisure, sitting in the sun or painting pictures on rocks, or training young wolves and little tigers to behave like peaceful domestic animals.

Of course in the very olden days; it was always possible to enslave a weaker neighbour and force him to do the unpleasant tasks of life. One of the reasons why the Greeks and Romans, who were quite as intelligent as we are, failed to devise more interesting machinery, was to be found in the wide- spread existence of slavery. Why should a great mathematician waste his time upon wires and pulleys and cogs and fill the air with noise and smoke when he could go to the marketplace and buy all the slaves he needed at a very small expense?

And during the middle-ages, although slavery had been abolished and only a mild form of serfdom survived, the guilds discouraged the idea of using machinery because they thought this would throw a large number of their brethren out of work. Besides, the Middle-Ages were not at all interested in producing large quantities of goods. Their tailors and butchers and carpenters worked for the immediate needs of the small community in which they lived and had no desire to compete with their neighbours, or to produce more than was strictly necessary.

During the Renaissance, when the prejudices of the Church against scientific investigations could no longer be enforced as rigidly as before, a large number of men began to devote their lives to mathematics and astronomy and physics and chemistry. Two years before the beginning of the Thirty Years War, John Napier, a Scotchman, had published his little book which described the new invention of logarithms. During the war it- self, Gottfried Leibnitz of Leipzig had perfected the system of infinitesimal calculus. Eight years before the peace of Westphalia, Newton, the great English natural philosopher, was born, and in that same year Galileo, the Italian astronomer, died. Meanwhile the Thirty Years War had destroyed the prosperity of central Europe and there was a sudden but very general interest in ``alchemy,'' the strange pseudo-science of the middle-ages by which people hoped to turn base metals into gold. This proved to be impossible but the alchemists in their laboratories stumbled upon many new ideas and greatly helped the work of the chemists who were their successors.

The work of all these men provided the world with a solid scientific foundation upon which it was possible to build even the most complicated of engines, and a number of practical men made good use of it. The Middle-Ages had used wood for the few bits of necessary machinery. But wood wore out easily. Iron was a much better material but iron was scarce except in England. In England therefore most of the smelting was done. To smelt iron, huge fires were needed. In the beginning, these fires had been made of wood, but gradually the forests had been used up. Then ``stone coal'' (the petrified trees of prehistoric times) was used. But coal as you know has to be dug out of the ground and it has to be transported to the smelting ovens and the mines have to be kept dry from the ever invading waters.

These were two problems which had to be solved at once. For the time being, horses could still be used to haul the coal- wagons, but the pumping question demanded the application of special machinery. Several inventors were busy trying to solve the difficulty. They all knew that steam would have to be used in their new engine. The idea of the steam engine was very old. Hero of Alexandria, who lived in the first century before Christ, has described to us several bits of machinery which were driven by steam. The people of the Renaissance had played with the notion of steam-driven war chariots. The Marquis of Worcester, a contemporary of Newton, in his book of inventions, tells of a steam engine. A little later, in the year 1698, Thomas Savery of London applied for a patent for a pumping engine. At the same time, a Hollander, Christian Huygens, was trying to perfect an engine in which gun-powder was used to cause regular explosions in much the same way as we use gasoline in our motors.

All over Europe, people were busy with the idea. Denis Papin, a Frenchman, friend and assistant of Huygens, was making experiments with steam engines in several countries. He invented a little wagon that was driven by steam, and a paddle-wheel boat. But when he tried to take a trip in his vessel, it was confiscated by the authorities on a complaint of the boatmen's union, who feared that such a craft would deprive them of their livelihood. Papin finally died in London in great poverty, having wasted all his money on his inventions. But at the time of his death, another mechanical enthusiast, Thomas Newcomen, was working on the problem of a new steam-pump. Fifty years later his engine was improved upon by James Watt, a Glasgow instrument maker. In the year 1777, he gave the world the first steam engine that proved of real practical value.

But during the centuries of experiments with a ``heat-engine,'' the political world had greatly changed. The British people had succeeded the Dutch as the common-carriers of the world's trade. They had opened up new colonies. They took the raw materials which the colonies produced to England, and there they turned them into finished products, and then they exported the finished goods to the four corners of the world. During the seventeenth century, the people of Georgia and the Carolinas had begun to grow a new shrub which gave a strange sort of woolly substance, the so-called ``cotton wool.'' After this had been plucked, it was sent to England and there the people of Lancastershire wove it into cloth. This weaving was done by hand and in the homes of the workmen. Very soon a number of improvements were made in the process of weaving. In the year 1730, John Kay invented the ``fly shuttle.'' In 1770, James Hargreaves got a patent on his ``spinning jenny.'' Eli Whitney, an American, invented the cotton-gin, which separated the cotton from its seeds, a job which had previously been done by hand at the rate of only a pound a day. Finally Richard Arkwright and the Reverend Edmund Cartwright invented large weaving machines, which were driven by water power. And then, in the eighties of the eighteenth century, just when the Estates General of France had begun those famous meetings which were to revolutionise the political system of Europe, the engines of Watt were arranged in such a way that they could drive the weaving machines of Arkwright, and this created an economic and social revolution which has changed human relationship in almost every part of the world.

As soon as the stationary engine had proved a success, the inventors turned their attention to the problem of propelling boats and carts with the help of a mechanical contrivance. Watt himself designed plans for a ``steam locomotive,'' but ere he had perfected his ideas, in the year 1804, a locomotive made by Richard Trevithick carried a load of twenty tons at Pen-y-darran in the Wales mining district.

At the same time an American jeweller and portrait-painter by the name of Robert Fulton was in Paris, trying to convince Napoleon that with the use of his submarine boat, the ``Nautilus,'' and his ``steam-boat,'' the French might be able to destroy the naval supremacy of England.

Fulton's idea of a steamboat was not original. He had undoubtedly copied it from John Fitch, a mechanical genius of Connecticut whose cleverly constructed steamer had first navigated the Delaware river as early as the year 1787. But Napoleon and his scientific advisers did not believe in the practical possibility of a self-propelled boat, and although the Scotch- built engine of the little craft puffed merrily on the Seine, the great Emperor neglected to avail himself of this formidable weapon which might have given him his revenge for Trafalgar.

As for Fulton, he returned to the United States and, being a practical man of business, he organised a successful steamboat company together with Robert R. Livingston, a signer of the Declaration of Independence, who was American Minister to France when Fulton was in Paris, trying to sell his invention. The first steamer of this new company, the ``Clermont,'' which was given a monopoly of all the waters of New York State, equipped with an engine built by Boulton and Watt of Birmingham in England, began a regular service between New York and Albany in the year 1807.

As for poor John Fitch, the man who long before any one else had used the ``steam-boat'' for commercial purposes, he came to a sad death. Broken in health and empty of purse, he had come to the end of his resources when his fifth boat, which was propelled by means of a screw-propeller, had been destroyed. His neighbours jeered at him as they were to laugh a hundred years later when Professor Langley constructed his funny flying machines. Fitch had hoped to give his country an easy access to the broad rivers of the west and his countrymen preferred to travel in flat-boats or go on foot. In the year 1798, in utter despair and misery, Fitch killed himself by taking poison.

But twenty years later, the ``Savannah,'' a steamer of 1850 tons and making six knots an hour, (the Mauretania goes just four times as fast,) crossed the ocean from Savannah to Liverpool in the record time of twenty-five days. Then there was an end to the derision of the multitude and in their enthusiasm the people gave the credit for the invention to the wrong man.

Six years later, George Stephenson, a Scotchman, who had been building locomotives for the purpose of hauling coal from the mine-pit to smelting ovens and cotton factories, built his famous ``travelling engine'' which reduced the price of coal by almost seventy per cent and which made it possible to establish the first regular passenger service between Manchester and Liverpool, when people were whisked from city to city at the unheard-of speed of fifteen miles per hour. A dozen years later, this speed had been increased to twenty miles per hour. At the present time, any well-behaved flivver (the direct descendant of the puny little motor-driven machines of Daimler and Levassor of the eighties of the last century) can do better than these early ``Puffing Billies.''

But while these practically-minded engineers were improving upon their rattling ``heat engines,'' a group of ``pure'' scientists (men who devote fourteen hours of each day to the study of those ``theoretical'' scientific phenomena without which no mechanical progress would be possible) were following a new scent which promised to lead them into the most secret and hidden domains of Nature.

Two thousand years ago, a number of Greek and Roman philosophers (notably Thales of Miletus and Pliny who was killed while trying to study the eruption of Vesuvius of the year 79 when Pompeii and Herculaneum were buried beneath the ashes) had noticed the strange antics of bits of straw and of feather which were held near a piece of amber which was being rubbed with a bit of wool. The schoolmen of the Middle Ages had not been interested in this mysterious ``electric'' power. But immediately after the Renaissance, William Gilbert, the private physician of Queen Elizabeth, wrote his famous treatise on the character and behaviour of Magnets. During the Thirty Years War Otto von Guericke, the burgomaster of Magdeburg and the inventor of the air-pump, constructed the first electrical machine. During the next century a large number of scientists devoted themselves to the study of electricity. Not less than three professors invented the famous Leyden Jar in the year 1795. At the same time, Benjamin Franklin, the most universal genius of America next to Benjamin Thomson (who after his flight from New Hampshire on account of his pro-British sympathies became known as Count Rumford) was devoting his attention to this subject. He discovered that lightning and the electric spark were manifestations of the same electric power and continued his electric studies until the end of his busy and useful life. Then came Volta with his famous ``electric pile'' and Galvani and Day and the Danish professor Hans Christian Oersted and Ampere and Arago and Faraday, all of them diligent searchers after the true nature of the electric forces.

They freely gave their discoveries to the world and Samuel Morse (who like Fulton began his career as an artist) thought that he could use this new electric current to transmit messages from one city to another. He intended to use copper wire and a little machine which he had invented. People laughed at him. Morse therefore was obliged to finance his own experiments and soon he had spent all his money and then he was very poor and people laughed even louder. He then asked Congress to help him and a special Committee on Commerce promised him their support. But the members of Congress were not at all interested and Morse had to wait twelve years before he was given a small congressional appropriation. He then built a ``telegraph'' between Baltimore and Washington. In the year 1887 he had shown his first successful ``telegraph'' in one of the lecture halls of New York University. Finally, on the 24th of May of the year 1844 the first long-distance message was sent from Washington to Baltimore and to-day the whole world is covered with telegraph wires and we can send news from Europe to Asia in a few seconds. Twenty-three years later Alexander Graham Bell used the electric current for his telephone. And half a century afterwards Marconi improved upon these ideas by inventing a system of sending messages which did away entirely with the old- fashioned wires.

While Morse, the New Englander, was working on his ``telegraph,'' Michael Faraday, the Yorkshire-man, had constructed the first ``dynamo.'' This tiny little machine was completed in the year 1881 when Europe was still trembling as a result of the great July revolutions which had so severely upset the plans of the Congress of Vienna. The first dynamo grew and grew and grew and to-day it provides us with heat and with light (you know the little incandescent bulbs which Edison, building upon French and English experiments of the forties and fifties, first made in 1878) and with power for all sorts of machines. If I am not mistaken the electric-engine will soon entirely drive out the ``heat engine'' just as in the olden days the more highly-organised prehistoric animals drove out their less efficient neighbours.

Personally (but I know nothing about machinery) this will make me very happy. For the electric engine which can be run by waterpower is a clean and companionable servant of mankind but the ``heat-engine,'' the marvel of the eighteenth century, is a noisy and dirty creature for ever filling the world with ridiculous smoke-stacks and with dust and soot and asking that it be fed with coal which has to be dug out of mines at great inconvenience and risk to thousands of people.

And if I were a novelist and not a historian, who must stick to facts and may not use his imagination, I would describe the happy day when the last steam locomotive shall be taken to the Museum of Natural History to be placed next to the skeleton of the Dynosaur and the Pteredactyl and the other extinct creatures of a by-gone age.