Exercise Pro

THE REAL beginning of the present age of machinery dates from Watt’s invention of the double-acting steam engine which was patented in 1782. Prior to that date the steam engine was used merely for pumping water, but now in its new form it was adapted for use in driving industrial machinery. But, as we have shown in another chapter, it was not until John Wilkinson invented his boring machine in 1774 that it was possible to bore the cylinders that Watt used in his engine. In the field of machine tools there were several notable inventions. Henry Maudslay invented the slide rest for lathes and later in 1797 the screwcutting lathe. Joseph Bramah invented the hydraulic press and Maudslay furnished the cup leather packing that made it a success. Woodworking machinery, and particularly mortising machines for making pulley blocks, were invented by Samuel Bentham and patented in 1791 and 1793. In the textile industry we find the spinning jenny invented by Hargreaves in 17

AT THE VERY beginning of this book we observed that war is a most potent stimulus to invention among primitive men. Despite all our advances in civilization we still have our wars, each more dreadful than the preceding one; for each important conflict brings forth new engines of destruction or stimulates the invention of new death-dealing machines which are developed during intervals of peace. So terrible has modern war become that with each great conflict it has seemed as if its very dreadfulness would stay the hand of the invader and make him hesitate to expose his men to the horrible monsters which science and invention have created. To-day, after a titanic struggle which cost millions of human lives, which destroyed billions of dollars’ worth of property, and which made itself felt to the remotest corners of the earth, serious efforts are being made to banish war, but at the same time inventors here and abroad are busy inventing new and more powerful engines of deat

IN THE preceding chapter we dealt with high temperatures and their employment in melting, molding, and working steel into useful forms. It will be well for us to pause here to consider temperatures at the other end of the thermometer scale, how they are obtained, and the important part they play in modern civilization. It is not absolutely correct to speak of producing “cold.” We are apt to forget that cold is merely absence of heat. Strictly speaking, there is nothing cold on earth. Everything is more or less hot. A piece of ice at 32 degrees F. is hot compared with a lump of frozen alcohol, and the latter at its freezing point is hot compared with a lump of frozen air, while air at its freezing point is hot compared with a lump of solid helium. In other words, frozen alcohol will be melted by the heat in the ice; frozen air will be melted by the heat in frozen alcohol, and frozen helium will be fused by the heat in frozen air. Everything contains heat, and one object

IN MARKED contrast to the massive machinery and apparatus described in the last chapter, and fully as wonderful, is a class of machinery to which we might apply the term “animated.” By this we do not mean manikins or toys, but certain higher types of machines which seem to be possessed of powers that we should expect to find only in living beings—machines that have a sense of touch, sight, and hearing—machines that will reason out a mathematical problem; that will talk; that have the equivalent of a memory. In this broad classification we may include such widely different machines as the motion-picture camera and projector, and that mysterious mechanism which seems animated with strange powers of its own—- the gyroscope. MATHEMATICAL MACHINES Adding, subtracting, multiplying, dividing, and the working out of complex mathematical problems by machine seems wonderful until we stop to reflect that mathematics is the most precise and mechanical of all sciences. In the simp