7 6 Mr. six’s Account of 
thermometer, without a touch, be immediately rectified for 
another obfervation. When I wifh to put the thermometer 
out of my hand, without hanging it up, I have a hand to 
place it on ; for if the mercury prefies againft the index, while 
the inftmment lies in an horizontal pofition, it is in danger of 
palling by it, which is avoided by keeping the thei mometer irt 
a pofition nearly vertical. To prevent the mercury fluffing its 
place in the fpirits within the tube (which I apprehended it 
might do on account of the fuperiority of its fpecific gravity, 
efpecially when kept for a confiderable time, very high on one' 
fide, and low on the other), l made that part of the fmall tube' 
from e to/ with the inner diameter exceeding fmall ; and found,, 
upon trial, that after the fummer’s heat had kept the mercury 
for a long time high on one fide, the winter’s cold brought it 
again as accurately to the freezing point on the other a3 at 
rirfl:*. This thermometer may be made a mercurial one by 
inverting the glafs, and filling- with mercury that part which 
in the firfl: is filled with fpirits, and with fpirits that part of 
the fmall tube from d to g which m the former is filled with 
mercury ; the indexes in either cafe may be the fame, and w ill 
be carried up in the lame manner upon the fur face of the mer- 
cury ; but the end of the tube at /, inflead of being fealed^ 
mull then be left open, and hand inverted in a bulb, or fmall- 
ciftern of mercury, into which the external air has free accefs. 
The diameter of the tube ab fhould be confiderably mcrealed 
if the degrees on the fcale are required to be as wide as thofe in 
the fpirit thermometers. It is indeed better in this cafe to 
have a double rather than a larger Angle tube ; but finding the 
weight of fo great a quantity of mercury in a thin glafs tube 
* With a thermometer of this fort I obferved the greateft heat and cold that 
happened every day and night throughout the year 1781. 
7 
attended 
