302 Answer to Dr. Murray’s Objection to -, [Aprit, 
thermometer with us, but I think the quicksilver would not have 
risen above 40°, 
The rising of the sun presented a magnificent scene, but quite 
different from that of the evening ; the whole surrounding country, 
except Ouva, was covered with clouds, above which only the tops 
of a few mountains were visible. Hunas Garree Candy, bore 25’ 
N. E.; and a mountain that we decided to be Idalgasina, 22° S. E. 
The whole country of Ouva was exposed to view, and lay stretched 
out in appearance just beneath our feet. The sea on that side was 
perceptible, and bore 8. E., which must have been in the neigh- 
bourhood of Paltoopane, and it was perhaps the Leway, or great 
natural Saltpan, that we observed. 
At seven in the morning we began to descend.the mountain, and 
reached Palabatula at noon. 
FR A LS EE 
ArTIcLE IX, 
Answer to Dr. Murray's Objection to Prevost’s Theory of Radiant 
Heat. By Richard Davenport, Esq. 
(To Dr. Thomson.) 
SIR, 
As you and Dr. Murray have done me the honour to discuss 
some arguments I had ventured to put together in explanation and 
confirmation of Mr. Prevost’s theory of radiant heat, applying the 
theory to some phenomena that had been deemed inconsistent with 
it, I hope you will allow me room in your Annals for a brief ex- 
planatory reply to Dr. Murray’s notice of my paper. 
“Let us suppose the metal canister of Dr. Murray’s experiment 
to be set on a stand in the middle of a room, with the polished 
side facing the north, the blackened surface facing the south. (I at 
present suppose it empty, and of an equal temperature with the 
walls of the apartment.) Then set one thermometer on the north 
side of the canister, and near it: and another on the south side, 
at the same distance. 
The canister intercepts from the north thermometer a large 
portion of radiant calorie emanating from the south wall of the 
apartment, and it intercepts from the south thermometer an equal 
quantity of that from the north wall. Neither of these thermo- 
meters will indicate any variation of temperature, although one 
surface of the canister radiate, and one does not. 
Dr. Murray does not account for this circumstance. I account 
for it on Mr. Prevost's theory, by saying, that the polished surface 
reflects frem the north wall as much as it intercepts from the south 
wali: and the blackened surface. gives by its own radiation as 
much as if intercepts from the north wall, The thermometers 
