To the SURFACES of BODIES. 35 



the hemifphere, moving with the correfponding velocity on the 

 fame line of the firft column ; and in the laft column are con- 

 tained the ratios of thefe two refiftances, or how often each 

 refiftance of the round fide is contained in that on the flat fide 

 of the hemifphere. 



10. From a flight contemplation of the lafl; three columns of 

 this table, we may eafily draw feveral important confequences. 

 As, firfi. From the fifth and fixth columns, it appears, that the 

 refiftance to either furface, with different velocities, is always as 

 the fquare of the velocity, as near as fuch experiments can be 

 expe(5led to fliow. 



Thus, in the fifth column, taking the refiftances correfpond- 

 ing to the velocities of 4 feet and 8 feet, which are as i to 2, 

 and their fquares as i to4; the refiftances 4.8 to 19. i are as 

 I to 4 very nearly ; and the refiftances in the fixth column, 

 namely, 2 to 8.2, are alfo nearly in the fame ratio. And fo of 

 others. 



11. idly. From the laft column, it appears, that the refiftance 

 to the flat fide is to that on the round fide, on an average, 

 nearly as 2.45 to i, or 2^ to i nearly, if a medium be taken 

 among all the numbers in the laft column. But, by the theory 

 of the refiftance of fluids, we are led to expedl, that this ratio 

 would have been only that of 2 to 1, inftead of 2 4 to i, as by 

 the experiment. Now, what this difference is owing to, may 

 be at prefent difficult to determine with precifion. The greater 

 part of it may probably arife from the air differing in its na- 

 ture from the perfedl fluid which the theory contemplates ; but 

 fome fmall part of it may arife from the different figure of the 

 hinder parts of the hemifphere, though I hardly fufpedl that 

 this may caufe any fenfible difference. I intend, however, foon 

 to try whether it be fenfible to experiments ; in which I intend 

 to employ a cylinder, to compare with the flat fide foremoft of 

 the hemifphere, and a whole fphere, each of the fame diameter, 

 to compare with the round fide foremoft of the hemisphere. I 



e 2 propoie 



