174 ANDROPOGON. 
of America. The sorrel-tree species, Andromeda 
arborea, is a tree forty feet high; the rigid spe- 
cies is a large shrub, twenty feet high; the moss- 
like species, the dwarf variety of the box-leaved 
species, the two varieties of the axil-flowering 
species, and all the five well-established varieties 
of the marsh species, Andromeda polifolia, are 
undershrubs not exceeding one foot in height; 
and all the other species and varieties are small 
shrubs of from two to six feet in height. Miller 
enumerates only five species; and Marshall only 
three. The marsh species, polifolia, is probably 
the best known; and the latifolia, erecta, speciosa, 
media, minor, axillaris, calycalata, latifolia, myr- 
tifolia, ventricosa, catesbeert, coriacea, and cerulea, 
are somewhat extensively diffused. All the more 
common species are easily propagated by suckers, 
by layers, or by foreign seeds.—Loudon’s Ency. 
of Plants.—Mawe’s Gardener’s Calendar—Muiller’s 
| Gardener's Dictionary.—Marshall on Planting. 
ANDROPOGON. A genus of exotic grasses, of 
the olyra tribe. Six species—the nerve-glumed, 
smooth-spiked, and the woolly—have been intro- 
duced to Great Britain; and about sixty other 
-species are known to botanists. The smooth- 
spiked is a native of the Cape of Good Hope, the 
| two-spiked and the woolly are natives of the 
south of Europe, and the other three introduced 
| species are natives of the Hast Indies. The two- 
| spiked and the woolly are hardy in Britain; the 
smooth-spiked is tender or half-hardy; and the 
| Hast Indian species can be cultivated only in the 
stove. The two hardy species grow to the height 
of 12and 18 inches. The lemon-grass species has 
an agreeable fragrance, and a warm, bitterish, 
and somewhat pleasant taste; and was formerly 
| imported from Turkey in bundles of about a foot 
| in length, and sold in shops as a stomachic and 
deobstruent. All the species are of easy culture. 
| ANDROSACE. A genus of small, hardy, hand- 
some, mountaineer plants, of the primrose family. 
Ten species have been introduced to Britain, from 
| Austria, Russia, Siberia, Switzerland, Italy, Den- 
mark, and the Pyrenees; and about twenty-five 
other species are known to botanists. Six of the 
introduced species are annuals; and one is a 
biennial. 
ANDRYALA,—popularly Downy Snow-Thistle. 
A genus of small plants, annuals, biennials, and 
perennials, of the composite family. They are 
natives of the south of Europe and the north of 
Africa. 
ANEMOMETER. An instrument for measur- 
ing the velocity of the wind. A farmer is more 
interested in the direction of the wind than in 
its velocity; yet in all situations, he has some 
interest in its velocity, and in such situations as 
the hollows, ravines, and gorges of an upland dis- 
trict, he has occasionally a great interest in it. 
The cooling power of wind is proportional to its 
the twisted, the lemon-grass, the two-spiked, the. 
velocity; and both that power, and the wind’s 
mechanical force, are sometimes of considerable 
ANEMOMETER. 
moment upon a farm. The mean force of the 
wind during the year is 0°855 at 9 a. m., 1:107 at 
3 P.M. and 0'605 at 9 p.m. A wind moving at 
the rate of one mile per hour is scarcely percep- 
tible; at 5 miles, isa gentle breeze; at 11, a plea- 
sant brisk breeze; at 22,a gale; at 35, a strong 
gale; at 50, a very strong gale; at 62, a storm; 
at 71, a great storm; at 88, a hurricane; and at 
110, a tornado, tearing up trees and throwing 
down houses. lLind’s anemometer, which has 
been considered the best, consists of two glass 
tubes, AB and CD in %g. 1. Plate II, about 
nine inches long, having a bore of =‘, of an 
inch. These are connected, at their lower ex- 
tremities, by another small tube of glass, with 
a bore of =5 of aninch. To the upper extrem- 
ity of the tube AB is fitted a thin metallic one, 
F, bent at right angles, so that its mouth may 
receive horizontally the current of air. A quan- 
tity of water is poured in at the mouth till the 
tubes are nearly half full, and a scale of inches 
and parts of an inch, HI, is placed betwixt the 
tubes. When the wind blows in at the mouth, 
the column of water is depressed in the tube 
AB, and elevated in the same degree in the 
other tube; so that the distance between the 
surface of the fluid in each tube is the length of 
a column of water, whose weight is equivalent 
to the force of the wind upon a surface equal to 
the base of the column of fluid. ‘The little tube 
which connects the other two is made into a 
small aperture, to prevent the oscillation of the 
fluid by irregular blasts of wind. But by a 
simple application of the hand, and a very brief 
and easy arithmetical calculation, the common 
thermometer may be used to ascertain accurately 
the velocity of the wind. “Mark the tempera- 
ture indicated by a thermometer in the still air; 
apply the hand to the ball till the alcohol rises 
a certain number of degrees; then mark the 
number of seconds that elapse till it fall exactly 
half the number of degrees raised. Raise the 
alcohol again the same number of degrees, and 
expose the ball to the full impression of the wind, 
and mark the number of seconds that it takes 
to fall half the number of degrees it rose. Divide 
the number of seconds elapsed in still air by the 
number of seconds elapsed in the full play of the 
wind, throw off 1 from the quotient, and multi- 
ply it by 45: the product expresses the velocity 
of the wind in miles per hour. For example: 
suppose the temperature in the still air is 50°, 
and that it is raised by the hand to 70°, and that 
it requires 100 seconds to cool down to 60°, or 
the half of the increase to which it was raised ; 
suppose that it is exposed to the current of the 
wind, and is raised to the same height, and cools 
down to 60° in 10 seconds, the example will stand 
thus ;—divide 100 by 10, which gives 10; throw 
off 1, and multiply 9, the remainder, by 44, which 
will give 403 miles per hour.” But this mode of 
measuring the velocity of the wind is subject to 
considerable error when the glass of the ther- 
