282 Proceedings of the Royal Irish Academy. 



value for the "drag" of air upon air, I shall take the average of all 

 six days, which give us — 



1 



J'' 



1. 28th May, 1879, 6317 



2. 30th „ „ 6339 



3. 31st „ ,, 5893 



4. 13th June, „ 5845 



5. 14th ,, ;, 6046 



6. 16th „ „ 5876 



Mean of all, f= . 



, J 6052-7 



T = 1-56 MiNTJTE.l 



Details of Experiments on Vartry Water. 



1. Zrd July, 1879. — Observed by Dr. Reynolds, using single 

 readings of one index : — 



n 



e 



Combination. 



I 



7 







110°-00 







1 



95-00 







2 



81 -00 







3 



69 -GO 







4 



58 -50 







5 



50 -50 







6 



42 -50 



(0,6) 



1 



295-6 



7 



36 -50 







8 



31 -00 







9 



26 -25 







10 



22 -50 







11 



19 -00 







12 



16 -00 



(0, 12) 



1 



291-6 





Mean, . . . . 



^ 293-6 





1 Some alterations (of a sligM kind) had been made in the mode of suspension of 

 the ball, after the trials in air. 



