668 Col. roy’s Experiments for 
ground end could be inferted into the focket with fuch a 
degree of force as to prevent it from being too eafily re- 
moved. The finger being then applied clofely to the 
open end of the tube, the whole apparatus was turned 
up, and placed over the ciftern into which the quickfilver 
had previoufly been put, great care being taken not to 
remove the finger till the lower extremity of the tube 
was fairly immerfed into the quickfilver; when that in 
the tube was permitted to defcend into an equilibrium 
with the atmofphere. In the firft experiment it was 
found that the water iffued by the eyes, and running 
down the fide of the veflel, fell into the ciftern. In order 
to remedy this inconveniency, a circular piece of tin was 
foldered round the upper part of it, immediately below the 
eyes ; and a flat fpout, projecting from it, ferved as a gut- 
ter to throw off the water from the ciftern, and from the 
lamps made ufe of to bring that in the veflel to boil. Six 
lamps, each with a double light, were fufpended around 
the trunk of the veflel, to heat the water as equally as 
poflible; though any irregularity of this kind was fuffi- 
ciently guarded againft, by conftantly mixing it during the 
operation. Another lamp of the fame kind flood under 
the ciftern, whereby the quickfilver there was kept at 
the temperature of the water in the veflel, each having 
its proper thermometer: this laft lamp was placed 
and 
