in the Mines of the Hartz. 4S7 
riation in his barometer from four to nine o’clock at 
night, which, at that height, indicated the greateft {la- 
bility in the {late of the air in all other refpeils, except- 
ing for the ordinary variations of the diurnal heat. Had 
it been on the Plain, the immobility of the barome- 
ter, in that part of the day, would have indicated that it 
had a tendency to defcend. I {hall not dwell on the caufe 
of this difference, which refults from that of the heights ; 
I have explained it in my work on the atmofphere. 
It was 4| h. when I made, at the entrance of the 
mine, the firll obfervation of the barometer and of the 
thermometer which accompanies it; and at the bottom 
of the firll ladder, that of the detached thermometer. 
Continuing to defcend we arrived at 54 h. towards the 
middle of the depth of the mine, near the beginning of 
a gallery 
ce qui, a cette hauteur, marquoit la plus grande ftabilite dans 1’etat de l’air, a 
tout autre egard que pour les variations ordinaires de la chaleur diurne. A la 
Plaine, l’immobilite du Barometre dans cette partie du jour, eut marque qu’ii 
tendoit a defeendre. Je ne m’arreterai pas a la caufe de cette difference, qui 
refulte de celle des hauteurs; je l’ai expliquee dans mon ouvrage fur l’atmo- 
fphere. 
II etoit 4| h. lorfque je fis a l’entree de la mine la premiere obfervation du 
barometre et du thermometre qui Paccompagne; et au bas de la premiere echetle 
celle du thermometre detache. Continuant a defeendre, nous arrivames a 5| h. 
vers le milieu de la profondeur de la mine, aupresKlu commencement d’uns 
S f f % galerii 
