1825.] 
closed; (3) by certain other vibratory 
cartilages, by which the true larynx is 
surrounded ; and (4) by cords or liga- 
mentous fibres, of great tensity, and 
muscles of exquisite sensibility. 
( To be continued. ) 
penta 
For the Monthly Magazine. 
Description of an Improyep Hycro- 
METER. 
NTIL the ingenious, scientific re- 
searches of Dalton, Howard and 
Foster developed new facts, and eluci- 
dated, by their discoveries, the laborious 
and patient observations of their prede- 
cessors, meteorological science assumed 
no prouder state than that of infancy. 
I believe we may now venture to nope, 
it has obtained constitutional stamina, 
which is likely to advance it, by united 
efforts, to, at least, a state of honourable 
adolescence. 
Nothing can be of more importance 
in meteorological pursuits than the pos- 
session of philosophical instruments, 
upon which may be placed strict reli- 
ance. But this is, unfortunately, far 
from being the case with a very great 
majority of our barometers, thermome- 
ters, &c. These, it would appear, are 
constructed by persons who have no 
regard to the objects of science, or even 
to the immediate purposes to which the 
instruments are afterwards to be ap- 
plied; and the consequence is, the 
manufacture, for sale, of a mere toy, or 
vile bauble, not one in a hundred of 
which is applicable to its pretended 
object. 
With regard to hygrometers, we are, 
perhaps, in a still worse condition; we 
have no such thing as a standard instru- 
ment of this description in use; and yet 
its importance to philosophical inquiry, 
and to meteorological science in par- 
ticular, is by no means inconsiderable. 
an equal complication of circumstances ; 
of which an explanation will hereafter be 
attempted. Two voices, or two instru- 
ments, may be in perfect unison, as to 
pitch, and may keep so, as far as taste and 
volition dictate, in the successive notes or 
melody—whose tones are exceedingly dif- 
ferent. How else do several instruments 
play, and several voices sing the same 
identical passage, at the same time, and 
produce that full effect of mingled modula- 
tion, in perfect harmony, which no number 
of similar instruments, or of instruments of 
unvaried voice (to exemplify by the adop- 
tion of an Italian idiom) could possibly pro- 
duce? Nay, cannot the human yoice be 
preserved in perfect unison, as far as relates 
to the scale, with many different instru- 
ments? Yet how distinct are the tones of 
the human yoice from those of any such 
imstrument ! 
Description of an improved Hygrometer. 
199 
Various kinds of this useful instrument 
have been fabricated, and most, if not 
all of them, I believe, found to be very 
defective. For myself, I am impressed 
with the idea of a similar necessity for 
our employing (particularly as respects 
comparative observation) an hygrometer 
constructed upon principles in confor- 
mity to a standard graduated scale, as 
for adapting the thermometrical scale of 
Fahrenheit. What the precise latitude 
or construction of this scale should be, 
I do not arrogate to myself the right of 
determining; but I will say, let it be 
as simple as possible, 
I will now describe an hygrometer, 
the simplicity and utility of which, I 
conceive, will be, at once, obvicus: it 
was first constructed, by me, about six 
years since, and, from that: period, has 
been of great use to me in various phi- 
losophical experiments and researches. 
Should it be thought to possess advan- 
tages over other and more complicated 
instruments of this kind, they will be 
found in its simplicity; its extreme deli- 
cacy; in the results of action being 
speedily obyious, in a manner imme- 
diately comprehended by the eye; in its 
portable structure; and, I think, general 
application. 
A, B, C, D, Fig. 1, represents a plain, 
smooth and polished piece of box-wood, 
about a foot in length, and half an inch 
in thickness, with a perforated brass- 
plate E, affixed behind, for the conve- 
nience of suspending the instrument.— 
F is a hollow brass-cup, for the recep- 
tion of a, Fig. 2; similar to those em- 
ployed in common self-registering ther- 
mometers, and which secures the part a 
from external derangement. The at- 
mospheric air must be permitted to have 
free access into this brass cup, at its 
upper part, around the lower extremity 
of the glass tube G, H.—I, K, Fig, 2, a 
glass tube of small bore (equal to those 
used for the small mercurial thermome- 
ter), open at both extremities, and the 
upper end, I, bent about half an inch, at 
right-angles with the long limb of the 
tube. The short part, I, fits into a hole 
at G, Fig. 1, by which it is suspended ; 
and its membranous appendage a, is 
concealed by the brass cup before men- 
tioned.— Vide G, H, Fig. 1. 
b, Fig. 1, is a small brass holdfast, for 
the more perfect security of the tube, 
firmly screwed on tothe box-wood 
frame. 
The scale L, M,N, O, requires but 
little description, it being simple, and its 
object obvious. 
a, Fig. 2, is the air-bladder of the 
common 
