[ *26 ] 
ufa efl Infelix familia : haec omnia fuam folverunt 
6. Morbus non fuit contaglofus. 
Vale, vir optiine ^ et benigne halce qualefcumque 
paginulas accipe. 
Laufannae Helvetiorum, 28 die Junii, 1764. 
XVIII. Ob fer vat ions for fettling the Propor^ 
iiony which the Decreafe of Heat bears 
to the Height of Situation* ExtraSled 
from a Letter of Thomas Heberden, 
M. D* F* R. S* to William Heberden, 
M*D. F.R.S. 
portion as we afcend the mountains here, induced 
me to make the following obfervations, with intention 
to difcover if there fubfifts any regularity between 
the difference of heat and the elevation of fituation. 
In order thereto, befides feveral obfervations made at 
different times, without any remarkable variation, I 
took the opportunity of a journey of fome Englifh 
gentlemen in Odober laff, whofe curiofity led them 
to afcend the mountain, called here Pico Ruivo, be- 
ing the higheft land on this ifland, the perpendicular 
height of which above the fea’s furface is, according to 
Mr. de la Luc’s method of menfuration by the 
barometer and thermometer, 5141 Englifh feet. 
Being fupplied by me with the proper inftruments. 
fymbolam. 
Read J 
H E remarkable tranfition from 
heat to cold in all feafons in pro- 
4 
and 
