390 PROCEEDINGS OP THE AMERICAN ACADEMY 



intention of the Association which offered the Medal. In order to get 

 a knowledo-e of the contents of the Exhibition, the manuscript cata- 

 logue was examined, and all exhibits that might be candidates were 

 noted and inspected. There was also distributed to the exhibitors the 

 following circular : — 



"' The Grand Gold il!fec?a?. — Boston, Oct. G, 1881. — The Commit- 

 tee appointed by the American Academy of Arts and Sciences to con- 

 sider the award of a Grand Medal, by the Massachusetts Charitable 

 Mechanic Association, " for the single exhibit most conducive to human 

 welfare," wish to obtain information for their guidance. If you desire 

 to compete for this Medal, please to state your claims by tilling the 

 following blanks : — 



" ' 1. Date of patent and time of introduction. 



" ' 2. Brief description of the exhibit, with a statement of the reasons 

 of its superiority, and of its contribution to human welfare. 



" ' Replies should be directed, before October 20, to Theodore Ly- 

 man, Chairman, American Academy of Arts and Sciences, Boston.' 



" The circulars returned were read and considered. When, by 

 gradual elimination, the candidates had been reduced to three or four, 

 special reports were prepared on them, and these reports were dis- 

 cussed at a meeting of the Committee. A ballot was then taken, 

 which resulted in the selection, by a unanimous vote, of the exhibit of 

 results of the ' testing machine,' now at the United States Arsenal in 

 Watertown, and designed and constructed by Mr. Albert H. Emery 

 (a civil engineer), as the ' single exhibit most conducive to human 

 welfare,' and therefore the proper one to receive the Grand Medal. 



" The purpose of the testing machine is to show the effect of a given 

 push or a given pull on any solid material. The specimen, placed 

 horizontally, is squeezed or pulled at pleasure, and the power at work 

 is measured in two forms : — 



" 1. The force used to hold the specimen in place, and that exerted 

 in the straining press, is indicated by a gauge. 



" 2. The strain on the specimen is shown by a weighing apparatus. 



" Considered purely as a testing machine, it is the latter apparatus 

 only which is directly important ; but viewed as a construction capable 

 of several uses (which uses are claimed by the inventor), the first con- 

 trivance or gauge becomes of consequence, because it can be applied 

 to measure with accuracy many sorts of pressure, such as that of steam 

 or that of the air. In like manner the weighing apparatus may, 

 mutatis mutandis, be used as a delicate scale. 



