Aqueous Vapour Atmosphere. 105 
remarks are presented to the Society pur- 
suant to the said intimation. 
The notion of an aqueous vapour atmos- 
phere as an agent distinct from the general 
atmosphere, was first announced by me in the 
paper on the constitution of mixed gases, 
read in October, 1801, and published in the 
5th volume of the Memoirs, part 2d.—Now 
if an aqueous vapour atmosphere, such as 
just mentioned, exist, it must be subject to 
the same laws as the atmosphere at large; 
that is, it must decrease in density in ascend- 
- ing in a geometrical progression to increments 
of height in arithmetical progression; or at 
least it must constantly be tending to that state. 
In order to investigate this fact, it would 
be desirable to ascertain the density of vapour 
at the heights of 1, 2, 3, 4, &c. miles above 
the earth’s surface. But as this is scarcely 
practicable, especially in this country; it 
occurred to me that observations made at 
such heights as are easily attainable would 
have their use, in as much as they would at 
least countenance if not demonstrate the 
idea I entertained, or else the reverse. 
As I had for some years been in the habit 
of allowing myself a week or two in summer 
for relaxation from professional engagements, 
and had generally spent the time in breathing 
o 
