CATALOGUE OF THE MECHANICAL ENGINEERING 



COLLECTION IN THE UNITED STATES 



NATIONAL MUSEUM 



MOTORS, LOCOMOTIVES, AND 

 SELF-PROPELLED VEHICLES 



EDITED AND COMPILED BY 



CARL W. MITMAN 



Curator, Divisions of Mineral and Mechanical Technology 



PART I. 

 AGENTS OF POWER. 



MECHANICAL ELEMENTS. 



The desire or the necessity of moving some heavy object, probably 

 a bowlder, led primitive man to the discovery of the lever and its 

 power to do work. His first application undoubtedly was that of 

 placing the end of a stick of wood or his ever-present club under the 

 object and pulling upward on the other end. Thus was born the 

 first mechanical element which has survived to the present day, and 

 may be seen in a variety of forms, both simple and complex, such as 

 the nail puller, can opener, scissors, cogwheel, typewriter action, etc. 



Next in order of discovery, probably, was the inclined plane, a 

 very old mechanical element, which is even to-day applied in mecha- 

 nisms of wide variety. An explanation advanced as to how the 

 placing of heavy stones in the building of the pyramids and temples 

 of ancient Egypt was accomplished is to the effect that inclined 

 roadways were built to the height desired and that the massive stones 

 were then drawn up and set in place. Two inclined planes, placed 

 back to back, form a wedge whose many uses need not be enumerated. 

 Then followed at intervals of time the roller, the pulley and block, 

 and the windlass, all coming into being as direct aids of muscular 

 effort. 



Model of Roller, Lever, and Inclined Plane. (Scale 1 : 6.) Made in the 



Museum. 



The combination of these three powers made it possible for the 

 engineers of antiquity in eastern and western nations to transport 

 and lift in place the heavy objects of which monuments and temples 

 were constructed. This ancient method is universally adopted for 

 transporting heavv loads. Cat. No. 181,251 U.S.N.M. 



9 



