8 0 Mr. six’s Account of 
ciding with the two ends of the column of mercuiy : then 
caufing the mercury to move (lowly on farther from the bulb, 
till that end of the column which was firft at d coincided with 
the mark at e, and letting it reft again, 1 made another maik 
at /; after which, caufing the mercury to move on as before, 
and continuing to mark its length at every part of the tube till 
it reached the end fartheft from the bulb ; by thefe means I 
obtained the feveral intermediate points on the line aa. Through 
thefe feveral points I drew dotted lines parallel to each other, 
and at right angles with the line aa to the line bb. Taking 
now, with a pair of compares, the wideft intervals between 
any of the dotted parallels, which in this cafe is fiom d to 
I inferted that diftance fucceffively between the feveral paral- 
lels, beginning at the loweft pair, as from d to e, from e to/, 
from / to g, and fo on to / 3 , as exhibited in the figure; and 
the aggregate of thefe lines may be confidered as one continued 
line, without any error of conlequence in this mattei. Having 
now the thermometer completely filled with mercury, the air 
expelled, the point of the fcale at 102°, and the freezing point 
properly taken * and marked upon the tube, which was now 
hermetically fealed, I again applied the tube to the line aa, 
and marked on that line the point of 102° and the freezing 
point. Through tliofe points I drew the lines //, kk 9 and 
divided that part of the compound line db included between 11 
* The freezing point, marked on the tube of this thermometer, is immediately 
taken by means of grated ice ; but the point of -ioo° by a ftandard mercurial 
thermometer, the upper point of the fcale of which was properly taken by boiling 
water, and the lower one by grated ice ; but it is m«re commodious in the firft to 
have the tube no longer than the air fcale, efpccially as the degrees are pietty 
wide. The method of a dj lifting the fcale to the inequality of the tube remains 
the fame, let the given points be at any diftance, or the divifions inueafed to any 
number. 1 
