622 RECORDS. 



weights six inches from the tread of the tire in a seven foot 

 driving wheel, travels above the locus of the driving axle, over 

 three times as far as it does below. 



The locus of the center of gravity of the crank pin for 24- 

 inch stroke of piston in a driving wheel of 7 feet diameter, 

 travels 44 per cent, more abo\'e the locus of the driving axle 

 than below. 



The above cited facts show that the relative velocities of the 

 center of gravity of the counter weights and crank pins are not 

 constant, for each portion of a revolution as in the stationary^ en- 

 gine, but are unequal and constantly changing. Therefore the 

 forces generated are unequal, and perfect counter-balance does 

 not obtain in the locomotive. Part of the unbalanced forces 

 must be absorbed by the locomotive, and part by the permanent 

 way. The upper portion of the driving wheel moves mucli 

 faster than the lower portion running on, and in contact with, the 

 rail, in striking contrast to the uniform velocity of the rim of the 

 fly wheel of a stationary engine. 



Mr. Dudley also showed lantern slides of running locomotives, 

 in which the lower spokes of the driving wheels were sharply 

 defined, while the upper ones, running so much faster, were not 

 stopped for the same exposure. 



The Section adjourned at 9.40 P. M. 



Theodore G. White, 



Secretary pro tcni. 



SECTION OF BIOLOGY. 

 January 9, 1899. 



Section met at 8 P. M., Professor Lee presiding. The min- 

 utes of last meeting of Section were read and appro\"ed. The 

 following program A\as then offered : 



Robert W. Shearman, The Skull of a Chlm.eroid. 



Richard Weil, Ax Anomaly in the Internal Course of 

 Trochlea Nerve. 



J. L. Wortman, History of the Development of the Can- 

 non-bone IN Artiodactyla. 



