[ 492 ] 
the pendulum was made to defcribe an arch of two- 
degrees ; and particular notice was likewife taken, in 
what fpace of time it had loft half a degree each vi- 
bration. Having then made the neceffary alterations 
for hanging the pendulum by a fpring, and particular 
care being taken that the pallets fhould fcape off 
from the wheel exactly at the fame angle as before, 
the pendulum being hung by its fpring, and made 
to vibrate thro’ an arch of two degrees, it was ob- 
ferved to loie half a degree in about half the time it 
did when turning upon edges. But, upon being 
fet a-going by the clock-work, the pendulum was 
found to defcribe an arch of near two degrees more 
than before : For, when it turned upon the edges, it 
defcribed an arch of only three degrees ; whereas, 
now it was hung by the fpring, it vibrated near five 
degrees y which was very different from what I ex- 
pected. 
This alteration being made; I foon found, that the 
clock went very regular j and, after a fuflicient trial, 
was fully fatisfied the pendulum would anfwer my 
expectations. But, fearing left I might be thought 
prejudiced in favour of my own invention, I engaged’ 
the Rev. Mr. Profeffor Blifs to make trial of it; and. 
accordingly, in the beginning of the year 1750, I 
fent to him, at Oxford, a clock for that purpofe ; 
and, in January laft, I received from him a letter, 
giving his opinion of it, of which the following (fo 
far as relates to the clock) is an exact copy. 
« S I R, 
“ I have now had thorough trial of the clock ; 
“ and am perfectly fatisfied, that your pendulum 
’ “ takes 
