Mr. six’s Account of an improved Thermometer. j j 
Charles cavendish and Mr. fitzgerald may be feen in 
the Pliilofophical Tranfaftions *. Though much ingenuity ap- 
pears in the invention of thofe curious inftruments, I could not 
forbear thinking, that a thermometer might be conftrudted 
more conveniently to anfwer the purpofe, and fihew accurately 
the greateft degree of heat and cold which happened in the 
obferver’s abfence. I therefore attempted to make one : with 
w r hat fuccefs I fubmit to your better judgement, and proceed to 
give a defeription of the inftrument. Fig. i. ab is a tube of 
thin glafs, about fixteen inches long, and five fixteenths of 
an inch in diameter ; cdefgh a fmaller tube with the inner 
diameter, about one fortieth, joined to the larger at the upper 
end b , and bent down, firft on the left fide, and then, after 
defeending two inches below a b , upwards again on the right, 
in the feveral diredlions cde,fgh , parallel to, and one inch 
diftant from it. On the end of the fame tube at h , the inner 
diameter is enlarged to half an inch from h to /, which is tw'o 
inches in length. This glafs is filled wutli highly' rectified fpi- 
rits of wine to within half an inch of the end /, excepting 
that part of the fmall tube from d to g, which is filled with 
mercury. From a view r of the inftrument in this ftate, it will 
readily be conceived, that when the fpirit in the large tube, 
which is the bulb of the thermometer, is expanded by heat, 
the mercury in the fmall tube on the left fide v r ill be prefled 
down, and confequently caufe that on the right fide to rife; 
on the contrary, when the fpirit is condenfed by cold, the 
reverfe will happen, the mercury on the left fide will rife as 
that on the right fide defeends. The ficale, therefore, which 
is Fahrenheit’s, beginning with o at the top of the left fide, 
has the degrees numbered downwards, while that at the right 
* Phil. Tranf. vol. L. p. 501. and vol. LI. p» 820. 
Vol. LXXII. L 
fide, 
