Great inventors have been working ever since Faraday’s time to improve and perfect the dynamo; some worked at collecting all the momentary induced currents into one smooth current always flowing in the same direction; others at providing ways and means for increasing the strength of the magnetic field or the speed of the engines. And thus to-day we have a vast industry occupying millions of men the world over, all due to a man who worked quietly and steadily in his laboratory, observing everything, neglecting nothing, and extracting the nuggets of golden truth from the mean-looking dust and dross of commonplace facts. [Illustration: Fig. 69.--Dynamos in an Electric Light Central Station.] Faraday made a great number of other discoveries. He investigated the connection between chemistry and electricity, and founded a new science called “electrochemistry.” He also studied the action of a magnet on light, and found that a strong magnet is able to give a certain twist to a beam of light while it passes through certain substances (such as sulphide of carbon). Whenever he made such a discovery he was transported with delight. He was always of a vivacious and merry disposition. He said of himself: “I was a very lively, imaginative person, and could believe in the Arabian Nights as easily as in the Encyclopædia; but facts were important to me, and saved me. I could trust a fact, and always cross-examined an assertion.” Towards the end of his life he suffered greatly from loss of memory. He helped himself by carrying about in his waistcoat pocket packets of cards, on which he wrote everything he wanted to remember. One of these has been preserved, and on it are found the following excellent maxims:-- “Remember to do one thing at once. Also to finish a thing. Also to do a little if I could not do much.” CHAPTER XV TELEGRAPHING WITHOUT WIRES