NOTES ON THE THIRD MEMOIR, PAGE 45. 169 



AVith ajar of 242 square centimeters in circuit, the discbarge contained 91 sparks, anil lasted bV"' 

 a second. The nictliod nsed and resnlts readied are described in his miMiioir in Vol. Ill, Nat. 

 Acad. Sci. 



Beetz, 1868, Pogg. Ann., devised a chronoscope by flashing the sparks of a Leyden jar charged 

 with static electricity from the style of a tuning-tork drawn orer a smoked snrface of tin-foil. He 

 snbsequently replaced the sheet of foil witli a metallic cylinder covered with smoked paper. With 

 this apparatus he measured the time of falling bodies, and obtained ±.001.5 of a second as the dif- 

 ference between the observed and computed times of fall. 



Rice, 1875, made seven determinations of the velocity of fowling-piece shot. The shot was of 

 numbers 2 and 7. With a charge of 3 drachms of powder and 1^ of No. 7 shot he obtained a mean 

 velocity, in a range of 50 yards, of 855 feet per second. He used in these experiments a Le 

 Boulangt^ chronograph. Professor Rice, U. S. N., was, 1 believe, the first to determine accurately 

 the velocity of bird-shot. His interesting paper is published in "Rod and Gun," July 31, 1875. 



Errata. 



In memoir "On a Method of Precisely Measuring the Vibrafory Periods of Tuning-Forks," &c., 

 Vol. Ill, Pt. II, of Mem. Nat. Acad. Sci., by Alfred M. Mayer, on pages 54, 55, and 50, wherever 

 "Tuileries fork" occurs read Feydeau fork, and wherever "Feydeau fork" occurs read Tuileries fork. 



S. Mis. 154 22 



