mometer is not of the thinnest kind employed by 
manufacturers. 
An instrument for ascertaining the wind’s ve- 
locity, described. in the ‘Lecons de Physique de 
L’Ecole Polytechnique,’ by Pujoulx, is shown in 
Plate I. Fig. 2, where AA is the section of a 
plane surface exposed to the wind, and fixed to 
the horizontal arm C, which moves in the cylin- 
der DD, which contains the bladder B, filled with 
air. This bladder is connected with the bent 
glass tube ¢#, containing a coloured fluid. When 
the wind blows against the surface AB, the cir- 
cular plate E presses against the bladder B, and, 
| by compressing the included air, forces it up the 
bent tube, and raises the coloured liquor. When 
the pressure upon the bladder diminishes, by the 
abatement of the wind, the bladder will recover 
its former figure, and the liquor will descend in 
_the tube. The graduation of this instrument 
| should be effected experimentally, by loading the 
_ surface AA with different weights in succession. 
The following contrivances by the writer of 
the article Anemommter in the ‘Edinburgh En- 
cyclopeedia,’ seem to possess several important 
advantages for measuring the velocity of the 
| wind. | 
| The first of these instruments is represented 
_in Plate IJ. Fig. 3, where A is a plane surface, 
to be exposed to the wind. It is fixed at right 
_ angles to the toothed rod AB, which drives the 
| pinion C. Round the axis D of this pinion, 
| winds a string DE, which raises the long cylin- 
drical weight F, out of a fluid contained in the 
glass vessel G. When the instrument is placed 
in the still air, and the weight F completely sub- 
merged in the fluid, the apparatus is in equilibrio 
| by means of a counter-weight fixed on the axis 
D, on the other side of the pinion, and the index 
points to o on the scale. When the anemometer 
is exposed to the wind, the toothed rod AB drives 
the pinion C, and thus raises the weight H out 
of the fluid. But it is evident that as the cylin- 
der E rises, its weight gradually increases, till it 
is completely raised above the fluid, when it has 
received an increase of weight equal to the weight 
of a column of fluid of the same size as the cylin- 
der. This variation of weight which the cylinder 
sustains, may be increased by augmenting its size, 
| or by employing a fluid of greater density. The 
length of the scale is obviously equal to the length 
of the cylinder, so that the circumference of the 
pulley or axis D should have the same length. 
The instrument may be accommodated to winds 
of any intensity, by varying the quantity of sur- 
face which receives the impression of the wind; 
and is graduated in the same way as other ane- 
mometers. 
The anemometer represented in /%g. 4, mea- 
sures the force of the wind by the effect which 
it produces in compressing a column of air, con- 
tained in the tube BC, and ball C. A short col- 
umn of mercury, or any coloured fluid, is placed 
at B, the beginning of the scale, and the force of 
three species have been introduced from foreign 
ANEMONE. 
the wind, concentrated by the conical mouth 
AB, forces the liquor up the tube, upon which 
the scale BOC is fixed for measuring the degree of 
compression, and consequently the force of the 
wind. An index made of iron, as in Six’s ther- 
mometer, may be made to float in the liquor, and 
remain in the part of the tube to which it was 
pushed by the wind. It is then drawn back to 
the fluid by a magnet, to be ready for another 
observation. If the greatest force of the wind 
which it is required to measure, should be able 
to compress a quantity of air into @ths of its 
bulk, then the contents of the tube BC should 
be a little more than 4th of the contents of the 
ball C, so that the greatest wind may just force 
the liquor within a little distance of the ball. 
The instrument shown in /%g. 5, depends on 
the same principle as the preceding, but is perhaps 
more commodious and accurate. The metal cap 
AB, bent at a right angle, is fixed upon the top 
of the glass tube, B, C, which communicates at 
C, with another glass tube, DE, of a much smaller 
bore, with a bulb, H, at its extremity. A quan- 
tity of mercury or any other fluid is poured into 
the tube BC, and of course rises to the same level 
mn, in both tubes... When the mouth A, of the 
instrument, is exposed to the wind, the fluid at 
m descends in the tube, and by rising in the stem 
DE, it compresses the enclosed air, till there is 
an equilibrium between the elasticity of the air 
and the force of the wind. In order to prevent 
the oscillation of the fluid, a round and thin piece 
of wood floats upon its surface at m. It is evi- 
dent, that the force which balances that of the 
wind, arises both from the elasticity of the air 
in the ball and the stem, and from the weight of 
the column of fluid, which is raised in the tube 
DE, above the fluid surface m, in the other tube 
BC: but as the scale may be formed by experi- 
ment, it is unnecessary to consider the effects of | 
these separate resistances. 
It is well known that when water is exposed to 
the wind, the quantity evaporated in a given 
time is proportional to the velocity of the wind, 
the capacity of the air for moisture remaining 
the same. If, therefore, we expose to the wind a 
plane surface A, /%g. 6, consisting of spunge or 
coarse flannel, stretched across a metallic frame, 
and saturated with water, and observe the quan- | 
tity evaporated in a given time, we have a mea- 
sure of the wind’s velocity. The square surface | 
A is fixed at the end of the lever BCD, moving | 
round C, as a centre, and the loss of weight is 
ascertained by the weight E moving along the 
arm OD. ‘The plane surface is turned to the 
wind by the vane G. This instrument furnishes 
us also with the means of determining the sum 
of the velocities of the wind during any given 
period. 
ANEMONE. A genus of small, ornamental, 
perennial plants, of the Ranunculus tribe. Four 
species are indigenous in Great Britain; twenty- 
