PLEASURES OF SCIENCE. 41 



come in contact with. Nay, the farm-servant, or day-labourer, whe- 

 ther in his master's employ, or tending- the concerns of his own cottage, 

 must derive great practical benefit, must be both a better servant, and 

 a more thrifty, and therefore comfortable, cottager, for knowing some- 

 thing- of the nature of soils and manures., which Chemistry teaches, and 

 something of the habits of animals, and the qualities and growth of 

 plants, which he learns from Natural History and Chemistry together. 

 In truth, though a man be neither mechanic nor peasant, but only one 

 having a pot to boil, he is sure to learn from science lessons which will 

 enable him to cook his morsel better, save his fuel, and both vary his 

 dish and improve it. The art of good and cheap cookery is intimately 

 connected with the principles of chemical philosophy, and has received 

 much, and will yet receive more, improvement from their application. 

 Nor is it enough to say, that philosophers may discover all that is 

 wanted, and may invent practical methods, which it is sufficient for the 

 working man to learn by rote without knowing the principles. He 

 never will work so well if he is ignorant of the principles ; and for a 

 plain reason : if he only learn his lesson by rote, the least change of 

 circumstances puts him out. Be the method ever so general, cases 

 will always arise in which it must be varied in order to apply ; and if 

 the workman only knows the rule without knowing the reason, he must 

 be at fault the moment he is required to make any new r application of 

 it. This, then, is the^rs^ use of learning the principles of science : 

 it makes men more skilful, expert, and useful in the particular kinds 

 of work by which they are to earn their bread, and by which they are 

 to make it go far and taste well when earned. 



But another use of such knowledge to handicraftsmen and common 

 labourers is equally obvious : it gives every man a chance, according 

 to his natural talents, of becoming an improver of the art he works at, 

 and even a discoverer in the sciences connected with it. He is daily 

 handling the tools and materials with which new experiments are to be 

 made; and daily witnessing the operations of nature, whether in the 

 motions and pressures of bodies, or in their chemical actions on each 

 other. All opportunities of making experiments must be unimproved, 

 all appearances must pass unobserved, if he has no knowledge of the 

 principles ; but with this knowledge he is more likely than another 

 person to strike out something new which may be useful in art, or 

 curious or interesting in science. Very few great discoveries have been 

 made by chance and by ignorant persons much fewer than is gene- 

 rally supposed. It is commonly told of the steam-engine that an idle 

 boy being employed to stop and" open a valve, saw that he could save 

 himself the trouble of attending and watching it, by fixing a plug upon 

 a part of the machine which came to the place at the proper times, in 

 consequence of the general movement. This is possible, no doubt ; 

 though nothing very certain is known respecting the origin of the story; 

 but improvements of any value are very seldom indeed so easily found 

 out, and hardly another instance can be named of important discover- 

 ies so purely accidental. They are generally made by persons of com- 

 petent knowledge, and who are in search of them. The improvements 

 of the Steam-engine by Watt resulted from the most learned investi- 



