This cleared up the matter at once for me, but I wished to complete the elucidation with an experiment. I began by giving him ten, then twenty, then thirty, then forty grammes of alcohol, up to eighty. I observed that his personality began to change after forty grammes. He became somewhat insolent and suspicious, and had vague delirious imaginings of persecutions. When invited to sing anarchistic songs he refused, evidently fearing to compromise himself, but sang them voluntarily in an undertone. When the dose of alcohol was increased to ninety grammes his personality seemed immediately to undergo a full change; his touch became twice as fine (three millimetres), and his visual field increased threefold; he declared that there was a spy around. When put into his cell he sang anarchistic hymns, threatened death to the king, handled a box as if brandishing a dagger, climbed to a window and insulted the sentinel, resisted five men who tried to disarm him, and continued in this condition for eight hours. The next day he denied having done any of these things, avowed that he was a good monarchist and a good citizen, and declared distinctly that he had not done what he had done, in the face of the concurrent testimony of several witnesses. On renewing the experiment a few days afterward with eighty grammes of alcohol, the same series of phenomena recurred--a real anarchistic raving, a genuine mania for regicide, which would certainly have ended in some act if he had not been restrained by force; and this person, who had at first presented an evident obtusity of touch and an extraordinary contraction of the visual field, now exhibited an almost normal touch of three millimetres and a visual field enlarged to triple its extent when he was sober. On the day after this he recollected none of all the things that had happened the day before. This double personality was determined in him by alcohol, as it is in others by misery or by fanaticism, while it rests with all upon a congenital basis. The fact helps us to explain how some inoffensive man may have a type of physiognomy quite similar to that of Ravachol, showing how often there are true criminals in potency, whose physiognomy, or rather the anomalies of it, bears a prophetic relation to the crime which breaks out on the first determining circumstance. And we have here another explanation of such contradictory characters as those of Ravachol, Caserio, and Luccheni, who, having been once well-behaved, end by becoming criminals. * * * * * Applied science was defined by Sir W. Roberts Austen, in his presidential address to the Iron and Steel Institute, 1899, as “nothing but the application of pure science to particular classes of problems.” WHAT MAKES THE TROLLEY CAR GO. BY WILLIAM BAXTER, JR., C. E. I.