FROM THE HIGHER ATMOSPHERE. 489 
a train of damp straw set on fire, was, from the difficulty of 
managing it, found to lead to no certain conclusion. 
But during winter, a much easier mode occurred for decid- 
ing the question. In a room where a steady fire was kept up, 
the sectoral aethrioscope was set on the inside of the window, 
and directed to the upper part of the opposite wall; but on 
throwing up the window, the instrument being now surround- 
ed by a body of cold air, which, however, did not penetrate far 
into the room, the liquor sank 5 or 6 degrees, indicating im- 
pressions of heat, caused evidently by the excess of tempera- 
ture of the remote air of the room above that which was con- 
tiguous to the aethrioscope. It need hardly be observed, that the 
effect increased in colder, and diminished in milder, weather. 
A similar experiment is readily performed by help of the erect 
zthrioscope. In a close apartment, where a good fire is con- 
stantly kept up, the ceiling and the floor may be discovered by 
the pendant differential thermometer to have exactly the same 
temperature with its adjacent stratum of air. Yet the upper 
portions of the confined air of the room will be found several 
degrees warmer than the lower. Instead of being divided only 
into opposite ranges, the whole mass, from the floor to the ceil- 
ing, will, in consequence of the expansion and buoyancy of its 
heated particles, form a series of intermediate strata, not dis- 
tinguished, however, by any very precise boundaries. But the 
intensity of action being proportional to the difference of tem- 
perature, the effect on the zthrioscope must evidently be the 
same, whether it is produced by a single set of large pulses or 
by several sets of smaller ones. If, for example, instead of one 
bounding surface, above which the air is seven degrees warm- 
er than immediately below it, we suppose seven such boundaries, 
each having an excess of temperature of only a degree: the 
pulses excited at the first of these intermediate surfaces, and 
‘successively augmented as they reach the second, third, and 
Vor. VIII. P. If. 3Q fourth, 
