289 
the mean density of the earth. 
being all a little above 5, excepting the third number, which 
is a little below 5. And immediately after, is the following 
remark, showing the author's doubt of their accuracy ; viz. 
“ From this table it appears, that though the experiments 
“ agree pretty well together, 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 cur- 
“ rent 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 vibration of 
“ the ball, I think it could not ; but as there will most likely 
“ be much irregularity in the current, it may very likely be 
“ sufficient to account for the difference.” It then proceeds : 
“ By a mean of the experiments made with the wire first 
“ used,” ( viz . the first six numbers or experiments) <s the 
“ density of the earth comes out 5.48 times greater than that 
“ of water ; and by the mean of those made with the latter 
“ wire, it comes out the same ; &c.” 
Now, though the former list of errata were but small in 
quantity, yet here is one of considerable magnitude, viz. in 
the medium of the first six experiments, said to be 5,48, which 
is very erroneous, the true medium being only 5.31 ; and it is 
rather curious that that medium 3.48 has been obtained, by 
taking the third experiment as 5.88 instead of 4.88, through 
mere oversight or carelessness. If this were the only error, 
it might perhaps be excused as a single accident ; but the 
whole will make a very different appearance, when we have 
shown that many small errors exist in almost all the numbers 
