492 ANNUAL EECOED OF SCIENCE AND INDUSTRY. 



of specimens, and the precise determination of mechanical 

 and physical properties, with a view to the deduction and 

 enunciation of laws connecting them with the phenomena of 

 resistance to flexure, distortion, and rupture. Subsequently 

 the board will enter upon more general investigations, test- 

 ing such specimens as may be forwarded to the president, 

 or such as it may be determined to purchase in open mar- 

 ket. Immediately upon the completion of the apparatus 

 ordered, circulars will be published giving detailed instruc- 

 tions relative to the preparation of specimens for testing, 

 and setting forth minutely the information which will be de- 

 manded previous to their acceptance. 



Engineers, scientists, and manufacturers throughout the 

 country are warmly urged to second the efforts of the com- 

 mission by imparting any information in their possession. 

 Those wishing to aid the work can procure the fullest in- 

 formation by addressing the secretary, Professor R. H. 

 Thurston, Hoboken, New Jersey. 



THE STRENGTH OF CEMENTS AND MOETAES. 



Surgeon E. Nicholson, of Bangalore, India, says that hav- 

 ing completed his cement-testing machine, he has made a se- 

 ries of experiments with a view of ascertaining what results 

 are given by it, not only with the ordinary materials, brick, 

 lime, and sand, but such new material as might be presented. 

 These experiments, which have extended over a very con- 

 siderable period, embraced a large range of substances, and 

 are especially instructive in respect to hydraulic mortars 

 and lime. He says that the addition of raw sugar {or jag- 

 gery) to the shell-lime mortars made at Madras has often 

 been mentioned, but the rationale of its employment is gen- 

 erally not correctly given. By some the advantage of sugar 

 is ascribed to its influence in retarding setting. By others 

 it is stated that the bad qualities of fat limes may be, in 

 some degree, corrected by sugar, as its influence is very 

 marked in the first solidification of the mortar. Captain 

 Smith says that mortars made of calcined shells have stood 

 the action of the weather for centuries because of the mixt- 

 ure of jaggery in their composition. Mr. Nicholson's own 

 experiments confirm those of Captain Smith in showing that, 

 while some increase of strength doubtless attends the use 



