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II. Description of an improved Hygrometer. By Mr. Thomas 
Jones. Communicated by Captain Henry Kater, F. R. S. 
Read June 1 6, 1825. 
The attention of the scientific world has been lately so 
much occupied in experiments on atmospheric phenomena, 
that it is hoped any simplification or improvement in the 
instruments employed for that purpose, may not be unac- 
ceptable. 
The principle of the hygrometer which I am about to 
describe, is that of enabling the observer, readily and accu- 
rately, to ascertain by direct and simple means, the degree of 
temperature at which the moisture of the atmosphere is con- 
densed, and the instant at which that operation commences. 
The hygrometer is composed of a mercurial thermometer, 
the graduated scale of which is about four inches and a half 
long ; at the lower part of the scale the glass tube is bent 
to form a right angle, at the end of which the bulb of the 
thermometer rises parallel to the scale, and about one inch 
from it ; the bulb is about one inch long, and of a cylindrical 
form, with a black convex top, the diameter of which is a little 
more than that of the cylindrical part, which is covered with 
silk. The scale is attached to a piece of cylindrical wire, 
three inches long, and turns upon a joint screw passing into 
its edge, the other end of which wire being placed in a 
tubular foot fixed to the inside of one end of the case, forms 
