the Depth of the Mines in the Hartz. 427 
was very high, the thermometer Hood at 3 1 \ of fahren~ 
heit; and the clouds, chafed by the wind, covered every 
thing with a cruft of ice that formed itfelf perceptibly to 
the eye. 
I had taken with me a new hygrometer, conftrufted 
upon the principles of that I had the honour to prefent 
to the Royal Society four years ago, but corrected in many 
things where experience had taught me better. I was in 
hopes, by taking it to the Hartz, of being able to repeat the 
experiment of the great drynefs of the fuperior regions 
of the air, which I had made formerly on the Alps ; but 
it happened quite otherwife, and I was not forry for the 
contrail. Being arrived at the top of the Brocken, I fuf- 
pended my hygrometer on the outlide of a fmall hut, 
which M. de verniguerode has had the humanity 
to ere£l for the benefit of fuch obfervers as Ihould 
come 
faifoit un vent afTez fort, le thermometre etoit a Fahrenheit; et les 
nuages charies par le vent, couvroient tout d’une croute de glace, qui fe formoit 
a vue d’oeil. 
J’avois porte avec moi un nouvel hygrometre, conftrult fur les principes de 
celui que j’ai eu l’honneur de prefenter a la Societe Royale il y a quatre ans; 
mais ou j’ai corrige pluheurs des defauts que l’experience m’a deja fait decouvrir 
dans ma premiere tentative, j’efperois en le portant au Hartz, de repfter 1’ ex- 
perience de grande fechereffe des couches fuperieures de i’air, que j’avois faite ci 
devant fur l’une des fommites des Alpes. Mais il en arriva tout autrement: et 
je ne fus pas fache du contrafte. Arrives done enfin au fommet du Brocken, je 
fufpendis mon hygrometre au dehors d’une petite hute, que M. de vernigue- 
rode a eu l’humanite de faire batir pour fervir de refuge aux curieux dans le 
Kkk 2 niauvais 
