2 BULLETIN 173, U. S. NATIONAL MUSEUM 



The material in the National Museum that illustrates the develop- 

 ment of mechanical power-producing devices is described in the 

 catalog that follows. The arrangement of the description is roughly 

 chronological by groups as indicated in the table of contents. The 

 brief and general summary of the development preceding each group 

 of descriptions is condensed and fabricated principally from the 

 published works listed in the bibliography. 



MECHANICAL ELEMENTS 



Engineering methods and equipment began with the first uses of 

 the so-called mechanical powers. These are the devices that, through 

 the interrelation of force, distance, and time, accomplish the more 

 convenient or the more effective application of effort. Usually in- 

 cluded in the term are the lever, the inclined plane, the roller, the 

 pulley, the wheel and axle, and the screw. Originally employed to 

 apply the muscular effort of animals and men, these simple devices 

 are today the elements of the complex combinations or machines that 

 harness resources of natural energy vastly greater than the combined 

 muscular energy of all the men and animals that have lived. 



It would be of interest to point to the invention of each of these 

 and trace its development to the present, but this is not possible. It 

 has been observed that a young wild orang will use a stick as a lever 

 to move stones, and that all these devices, including a semblance 

 of the screw, were known independently to one or another of the 

 primitive races around the world. It is supposed therefore that the 

 mechanical powers were used by man earlier than the li^nits of our 

 historical or archeological knowledge. 



The lever, the roller, and the inclined plane occur in nature and 

 were probably the first mechanical powers used by man. The rowing 

 oar, which is a simple application of the lever, is shown in Egyptian 

 drawings of 3000 B. C; Aristotle (B. C. 384-322) discussed the laws 

 of levers; Archytas (fl. 400 B. C.) wrote of the screw and pulley; 

 and Archimedes (B. C. 287?-212) is said to have used a screw as a 

 jack or as a pulling device to launch a ship for Herot. 



Practically all manual labor is still applied through the medium 

 of simple mechanical powers, and the total manual or muscular 

 energy expended through them is greater today than ever before. 

 Spoons, faucet levers, tool handles, gear shift levers, steering wheels, 

 typewriter keys, golf clubs, doors, and controller handles are aU 

 common examples of simple mechanical powers. 



