MANUAL WORK. 387 



the Theoretische Kinematik, that there is, so to 

 say, a philosophy of all possible machinery. 

 Each machine, however complicated, can be 

 reduced to a few elements plates, cylinders, 

 discs, cones, and so on as well as to a few 

 tools chisels, saws, rollers, hammers, etc. ; 

 and, however complicated its movements, they 

 can be decomposed into a few modifications of 

 motion, such as the transformation of circular 

 motion into a rectilinear, and the like, with a 

 number of intermediate links. So also each 

 handicraft can be decomposed into a number 

 of elements. In each trade one must know how 

 to make a plate with parallel surfaces, a cylinder, 

 a disc, a square, and a round hole ; how to 

 manage a limited number of tools, all tools 

 being mere modifications of less than a dozen 

 types ; and how to transform one kind of mo- 

 tion into another. This is the foundation of all 

 mechanical handicrafts ; so that the knowledge 

 of how to make in wood those primary elements, 

 how to manage the chief tools in wood-work, 

 and how to transform various kinds of motion 

 ought to be considered as the very basis for the 

 subsequent teaching of all possible kinds of 

 mechanical handicraft. The pupil who has 

 acquired that skill already knows one good 

 half of all possible trades. 



Besides, none can be a good worker in science 



