o f Edinburgh , Session 187 4-7 5. 517 
Depth in feet 
Observed temp. 
Calculated 
Diffs. 
from surface. 
Fahrenheit. 
boiling-point. 
36 
243° 
250°-9 
7 0, 9 
39 
247° 
252°*2 
5°*2 
45 
250°-5 
257° 
6°*5 
49-5 
254° 
260°*2 
6°*2 
54 
256°-5 
263°-3 
6°-8 
58*5 
254° 
266°*5 
12°-5 
67-5 
*259°*5 
272°-2 
12°-7 
77 -5 
257° 
278° 
11° 
* Mean of two observations 
Bunsen s Measurements in 1846. 
6th July, 
8.20 p.m. 
7th July, 2.55 p.m. 
7th July, 7.58 p.m. 
Height from 
Temp. 
Height from 
Temp. 
Height from 
Temp. 
bottom, in feet. 
Fahr. 
bottom, in feet. 
Fahr. 
bottom, in feet. 
Fahr. 
0 
254-5 
0 
261-5 
0 
259-7 
15-75 
252-8 
16-4 
253-4 
31-5 
235-4 
29-5 
248-7 
32-3 
251-2 
47-25 
186-4 
48-36 
223-5 
48-36 
230-0 
63 
180-7 
64-1 
185-4 
64-1 
184-5 
For comparison I give above Bunsen’s results from the “Annalen ” 
(1847), with the readings reduced to the same measures as my own. 
His heights are from the bottom ; no doubt, because for some time after 
a great eruption the level of the water in the funnel is gradually 
rising. While I remained, the basin continued nearly full, the 
level of water in it not changing more than a few inches. 
Bunsen draws the following conclusions from these observations: — 
(1.) That, omitting small irregularities, the temperatures in the 
Grey sir- column diminish from beneath upwards. 
(2.) That the temperature at all points is dependent on the time 
since last eruption. 
(3.) That that temperature nowhere reaches the boiling-point 
due to the pressure until a few minutes before a great eruption. 
(4.) That the temperature about the middle height of the 
column comes nearest to the boiling-point corresponding to the 
