Atmosphere of Rooms in a Tropical Climate. 23 
to be compressed by a forcing-pump into a close vessel, then 
cooled or rather deprived merely of its acquired heat of 
compression, and then being allowed to escape into the room 
desired to be cooled, would issue at a temperature as much 
below that of the atmosphere as it had risen above on com- 
pression. 
That this was a vera causa there was no doubt; the swufi- 
ciency and the practicability were the only matters of doubt. 
These the author attempted to solve, by shewing the quan- 
tity of increase of heat due to a certain amount of compres- 
sion; and by devising the most convenient form of the ne- 
cessary apparatus, and concluded that a one-horse power 
should supply a room with 30 cubic feet of air per minute, 
cooled 20° below the surrounding atmosphere. The various 
sources of mechanical power likely to be met with in warm 
countries, were then described ; and particularly a new and 
simple, and at the same time, a remarkably compact and 
effective form of windmill; as the wind is everywhere so 
cheap and abundant, and in the tropics so certain a species 
of moving power. Methods also of ventilating the cooled 
room, ?@. é., of keeping it constantly supplied with cooled fresh 
air, and removing the vitiated, were explained, as well as a 
natural principle for meeting the residual difficulty that might 
be expected to arise in some cases, viz., the too great mois- 
ture of the cooled air.—(Proceedings of the Royal Society of 
Edinburgh, 1849.) 
Examination of Professor E. Forbes’ s Views on the Geographical 
Distribution of British Plants. By A. D’ArcurAc.* 
Mr Edward Forbes, whose important researches on the 
distribution of animals in the depth of the sea we have al- 
ready referred to,t has considered the English flora in a point 
of view which connects it with geology, and more particularly 
* Histoire des progrés de la Géologie de 1834 421845. Paris, 1848. T. 2, p, 128. 
t Vol. i., p. 397. 
