52 



MEMOIRS OF THE NATIONAL ACADEMY OV SCIENCES. 

 Table VII — Continued. 



(7)— (1)— 6=255.92 



(8)— (2)^6=255. 88 



(9)— (3)— 6=255. 95 



(10)— (4)— 6— 255.85 



(11)— (5)— 6=255.98 



Meau 255.916 



Corr. for temp . . . -|-.192 



. (7)— (1)— 6=255.88 



(8)-(2)^ 6=255.95 



(9)— (3)— 6=255.82 



(10)— (4)— 6=255.95 



(11)— (5)— 6=25.5.93 



(12)— (6)— 6=25.5.90 

 (13)— (1)— 12=2.5.5.91 



256. lOS 

 Corr. for clock . . . — .028 



256. 080 



Mean . . '. 



Corr. for temp . . . 



Corr. for clock . . . 



.2.55.906 

 . +.192 



256. 098 



. —.028 



256. 070 



The mean value of tlie above- determiued ten means is as follows: 



The coirectiou — .026 lor the effect of support and scrape of style of fork was determined as 

 follows: 



The standard TIT-^ fork was placed in the same support {H of Fig. 1) which held it while it 

 made its record on smoked paper, but fork vibrated freely, that is, it did not trace its vibrations 

 on the paper. Another similar Ul\ fork was screwed on its resonant bo.\ and its prongs loaded 

 with wax till it made al)out five beats per second with rtrst fork. The beats were counted by 

 coincidences with the one-tifth second beats of a watch. 



Table VIII. 



Coiucidenoe.s were marked at 32 secomls; :i9 .seconds; 43.5 seconds ; 49 seconds; 54.5 seconds; 61.5 seconds. 



61.5 — 32^29.5; 29.5— 5^5. 9^time of one interval between coincidences. 



Kksumi':.— (1)=5.9 seconds; (2)=6.2 seconds; (3)=6.2 seconds; (4)=6.2 seconds. Mean=6.13=timo of one 

 interval between coincidences. 



In tbis time, tbe watch makes 6.13x5=30.65 beats, and the forks make 30.65+1^31.65 beats. Hence tbe 

 number of beats per second is 31.65— 6.13=5.16:i. 



We now made similar experiments to tbe above, with tlie dirt'erence that the standard UT3 

 fork was allowed to make its trace on the smoked j)aper, as it did when we determined its rate of 

 vibration. 



