for adjujiing 'thermometers . 
Rules to he obferved in adjujiing the boiling point . 
The moft accurate way of adj ufting the boiling point 
is, not to dip the thermometer into the water, but to ex- 
pofe it only to the fteam, in a veffel clofed up in the 
manner reprefented in fig. 4. where K&ba is the veffel 
containing the boiling water, r> d the cover, e a chimney 
made in the cover intended to carry off the fteam, and 
mm the thermometer pafled through a hole in the cover. 
Thofe who would make ufe of this method muft take 
care to attend to the following particulars. 
1 ft, The holing point muft be adjufted when the ba- 
rometer is at 29.8 inches unlefs the operator is willing 
to corredt the obferved point in the manner directed 
below. 
2dly, The ball of the thermometer muft be placed at 
fuch a depth within the pot, that the boiling point fhall 
rife very little above the cover; for otherwife part of the 
quickfilver in the tube will not be heated, and therefore 
the thermometer will not rife to its proper height. The 
furface of the water in the pot alfo fliould be at leaft one 
or two inches below the bottom of the ball ; as otherwife 
the water, when boiling faft, might be apt to touch the 
ball: but it does not fignify how much lower than that 
the furface of the water may be. 
