Y0L. LXXXVIII.] 



PHILOSOPHICAL TRANSACTIONS, 



405- 



CONCLUSION. 



The following Table contains the Result of the Experiments. 



From this table it appears, that though the experiments agree pretty well to- 

 gether, yet the difference between them, both in the quantity of motion of the arm 

 and in the time of vibration, is greater than can proceed merely from the error of 

 observation. As to the difference in the motion of the arm, it may very well be 

 accounted for, from the current of air produced by the difference of temperature ; 

 but whether this can account for the difference in the time, of vibration, is doubtful. 

 If the current of air was regular, and of the same swiftness in all parts of the vibra- 

 tion of the ball, I think it could not ; but as there will most likely be much irregu- 

 larity in the current, it may very likely be sufficient to account for the difference. 



By a mean of the experiments made with the wire first used, the density of the 

 earth comes out 5.48 times greater than that of water ; and by a mean of those 

 made with the latter wire, it comes out the same ; and the extreme difference of the 

 results of the 23 observations made with this wire, is only .75 ; so that the extreme 

 results do not differ from the mean by more than .38, or -V of the whole, and 

 therefore the density should seem thus to be determined, to great exactness. It 

 may indeed be objected, that as the result appears to be influenced by the current 

 of air, or some other cause, the laws of which we are not well acquainted with, this 



