‘ 
202 Mr. Murray on Ebullition of Water at different Altitudes. 
It will on proper calculation be seen that, though I pretend 
not to the niceties pointed out in Mr. Wollaston’s ingenious 
paper, (the circumstances under which the experiments were 
made precluding such accuracy, and I had not indeed the en- 
tire provision of apparatus constructed by this philosopher, ) 
ruder apparatus subserving my purpose,—that a distant ap- 
proximation to the altitude, as indicated by the barometer at 
three elevations, is only insured. 
In consequence of the capricious results indicated by my 
experiments on the ebullition of water at the village of Sim- 
poln on the Simplon, I made a series of experiments with the 
thermometer on hot water contained in a tumbler. I subjoin 
the results of five of these experiments. 
—_ 
. Ball of thermometer touching the surface . 131° 
Ditto completely immersed. . . . . . 135 
Ditto touching the bottom of tumbler . . 131 
2. Ball in contact with the surface. . . . . 131° 
Ditto immersed). 62) F ON on 20184808 
Ditto bottom: 24h) Oise La ea PREG 
ScBallion-sumibces? f°. 3nes.. os te core a 
Wittasdmmensed 2.) 1°...2b Sh sciecia'o . japon et 
Dies :battonr Ss. etdacstiiw coletiounet. . dé 
Ai RL, GORPSBITARE tacit fas roleweciiie “co. aah eee 
Ditto-smme#rsed..< « gu. 1. Merlgen no be be Sekbie Olkeo 
Ditto bottom wiMeciog lier shisthoc ake kes Ee 
5, Santon surmce: 2. ee Oe So Ooo eaam 
VITO TMMETSEC —s_ caL aces rare o Niece meets a ee 
Ditto bottom “Og oS AR RSS ee oe 
In one experiment I found a difference of 1° 5! Fahr. be- 
tween the centre portion of the superior surface of the water 
and the sides. . In another experiment, the difference amounted 
to 2° 5! Fahr. 
The following I presume to be the conditions that must in- 
terfere with anything like accuracy in thermo-barometrical 
indications of this kind in elevated regions. 
1. The hygrometric state of the incumbent atmosphere at 
the time the observation is taken. 
2. The attenuated pressure on the bulb of the thermometer, 
by which its form and dimensions must necessarily be altered. 
3. The water used must be more expanded in volume at 
great altitudes, than on the level of the sea, its density being 
therefore 
