- XII. 4 DescripTion of aa IMPROVED THERMOMETER. Com- - 
municated by DANIEL RUTHERFORD, M.D. F.R.S. Epin.: 
Profeffor of Medicine and Botany in the Univerfity of Edin- 
burgh. 
[Read April 5. 1'790-] 
“JHE following improvement on the conftruction of the 
thermometer, by which it is fitted to mark the loweft or 
the higheft point to which the fluid has attained in the abfence 
of the obferver, is due to JoHN RUTHERFORD, M. D. of Middle 
Balilith. This gentleman communicated it to me fome time 
ago, and accompanied the defcription with one of his thermo- 
meters. The contrivance is fo very fimple and,ingenious, that 
it well deferves to be made public. I therefore, by permiffion 
of the author, beg leave to lay an account of it before the 
Royal Society. 
1. Ir it be required, that the thermometer fhould mark the 
loweft point to which the liquid has defcended within any given 
time, a common fpirit of wine thermometer muft be provided, 
of a convenient fize, fuch as is reprefented by the figure A B *. 
Into the tube is introduced a {mall conical piece of coloured 
- glafs or enamel, (C), with its point turned towards the bulb of 
the thermometer. This piece is about } inch long, and of fuch 
diameter at the bafe, that it may move freely within the tube, 
yet 
* See the figure, plate 4. at the end of No. XIII. 
