( 4 ^ ) 
The two Clocks. being firmly skrewed to a Pafty* 
Wall, 1 began to make the tirlf Trial of this Kind of 
Pendulum, December 1721. and, hy January 
third, perceiving the Pillar ot Quickfilver conhderably 
too long, 1 procured a (liorter Glafs, which I got ready 
by the eighth, and made ufe of, until the Beginning 
of June following : By which Time I was weilTatis- 
fied of the Advantage of the Contrivance, notwith- 
ttanding both thefe Pendulums were bat rudely exe- 
cuted, and thi lafl had the Pillar of Quickfilver too 
fliort, but much nearer the true Length than the firft. 
This encouraged me to provide another Giafs, a little 
longer than the lafl, and to bellow more Care upon 
all the Parts of the Pendulum that required Exaclnefs. 
This being finifned, by the 9th oijime^ I began then 
to obferve the Motion of the Clock, by the Tranfits 
of the fixed Stars, as often as the Weather permitted, 
making ufe of a Telefcope which moved in the Plane 
of the Meridian , with this Inflrument I could be hire 
of not erring above two Seconds in Time. The Clock 
was kept conflantly going, without having either the 
Hands or Pendulum alter’d, from the 9th of June^ 
iy22. to the 14th of 1725. being three Years 
find four Months, 
For the firfl Year, I wrote down every Day, the 
Difference between the two Clocks, with the Heighth 
of the Thermometer, not omitting the Tranfits of the 
Stars, as often as it was clear. The Refult of all the 
Gbfervations was this. That the Irregularity of the 
Clock, with the Quickfilver Pendulum, compared with 
the Tranfits of the Stars, exceeded not, when greatefl, 
a fixth Part of that of the other Clock with the com- 
mon Pendulum ^ but for the greatefl Part of the Year, 
not above an eighth or ninth Part^ and even this 
Quantity would have been lelTened, had the Pillar of 
z Mercury 
