BY KOBEBT L. JACK, F.G.S., F.R.G.S. IX 



ing. There lies prepared for bis hand the already-known 

 power of steam ; and the paddle-wheel and screw propeller 

 ultimately shape themselves in the mind of the inventor. But 

 infinitely greater achievements have rewarded, although it may 

 be indirectly, the efforts of those who only felt the one greatest 

 need of all, the need of knowledge. It is no detraction from the 

 merit of the inventor of the screw propeller to say that if he was 

 the father of the invention, its ancestral line comprises a host of 

 worthies who solved abstruse mathematical problems, weighed 

 air, experimented on methods of controlling the expansive power 

 of steam, mvestigated the laws of the mechanics of fluids, and 

 so on and so on, for indeed the last of the line, like the 

 apparition seen by Macbeth, seems to " bear a glass, which shows 

 us many more." 



Perhaps the mind of a young man is first induced to 

 question the usefulness of science while he is painfully acquiring 

 the rudiments of mathematics. Perseverance in the study, 

 however, will soon convince him that he has come into posses- 

 sion of a tool which will open to him the doors of geography, 

 astronomy and physics ; that he can measure the heights of 

 mountains on which no human foot has trod, or the distance of 

 suns which sent off rays of light by which he detects their 

 presence ages before he was born, and determine the form, the 

 weight and the motion of his own and other worlds, or step 

 down into the regions of every-day life among the "practical 

 men " and gauge casks, survey land, or calculate the force 

 exerted in any given operation, or the strength of material 

 necessary for a certain duty. And the man so equipped finds, 

 " as the day wears and door succeeds door," that he may " spend 

 the whole day in the quest," " with such suites to explore, such 

 closets to search, such alcoves to importune 1 " * 



The advantages of a knowledge of chemistry are vaguely 

 recognised even by those who tliemselves know little of its 

 achievements or aspirations. Until quite modern times chem- 

 istry confined itself mainly to attempts to produce the precious 

 metals, and pursued this object with an assiduity worthy of the 

 praise of utilitarians, and the result was small. It was not till 



* Browning. 



