ANDRONICUS—ANEMOMETER.
afterwards Alexius himself, with whose widow he
contracted an indecent marriage. His reign, though
short, was vigorous, and restored prosperity to
the provinces; but tyranny and murder were its
characteristics in the capital. He set no bounds to
the gratification of his revenge against all who had
ever offended him, and his j ealousy of possible rivals
was equally sanguinary. At last, a destined victim,
Isaac Angelus, one of his relatives, having fled to
the Church of St Sophia for sanctuary, a crowd
gathered, and a sudden insurrection placed Isaac on
the throne, whilst A., now 73 years of age, was
put to death by the infuriated populace, after
horrible mutilations and tortures, on September 12,
1185. He was the last of the Comneni that sat on
the throne of Constantinople; but the succeeding
Dukes and Emperors of Trebizond were descendants
of his son Manuel.—A. II., the son of Michael Palseo-
logus, ascended the throne in 1283; but after a weak
and inglorious reign, was driven from it in 1328 by
his grandson, A. IIL., who, after a reign equally
inglorious, died in 1341, During these reigns, pro-
vince after province was conquered by the Turks.
ANDRONI'CUS—surnamed CYRRHESTES from
his birthplace, Cyrrhos in Syria—is said to have
erected the octagonal tower called the Tower of the
Winds at Athens, a building of the 3d or 2d c. B.c.
It probably received its name from figures repre-
senting the eight principal winds, and from a brazen
Triton which surmounted it, and shewed the direc-
tion of the wind—the first known weather-cock.
ANDRONI'CUS of Rhodes, a Peripatetic philo-
sopher, lived at Rome in Cicero’s time, and employed
himself in criticising and explaining the works of
Aristotle, a great number of which he was probably
the means of preserving to us. None of the writings
of A. himself are extant; for the works ascribed %o
him are probably the productions of Andronicus
Callistos, a learned Greek of the 15th c., who taught
the Greek language in Ttaly and France.
ANDROPO'GON. See LEMON-GRASS.
ANEGA'DA, the most northerly of the Tesser
Antilles, its lat. being about 19° N., and its long.
between 64° and 65° W, It contains about 13 square
miles, with a scanty population
of little more than 200. It
belongs to England. It is of
coral formation, being, like most
islands of the kind, low and
beset by reefs. One reef in par-
ticular, which runs out 10 miles
wood by a screw at the bottom. When the instru-
ment is used, water is poured into the tubes until
the level in both stands at the middle of the scale.
When no disturbing force acts upon either column
of liquid, the level of both is accurately the same ;
but when the mouth of the tube AB is turned
towards the wind, the column in AB is pressed
downwards, and that in CD rises proportionably,
and the difference of the heights of the two columns
gives the column of water which the force of the
wind sustains. Now, as we know that the pressure
of the atmosphere at the earth’s surface supports a
column of water about 33 feet high, or presses with a
force of about 2060 1bs. on the square foot, this instru-
ment gives us immediately the data from which we can
calculate the pressure or force of the wind. Thus,
suppose the wind to blow with a force sufficient to
raise the one column one inch above the other, we
have 7'z of 3'5 of 2060, or about 525 Ibs. of pressure
on the square foot as the force of the wind.
The following table gives approximately the rela-
tion of the height of the water in the A. to the force
and velocity of the wind in winds of different
characters. (See AERODYNAMICS.)
Height of Pressure per Velocity
Water. Square Foot. per Hour,
e ‘ Tsis Gl &
Feeble Wind, . s 1Ny Too 1os. 41¢
Fresh Breeze, . + 13 164
Very Strong Wind, 1 . 5F5 324
Tempest, . : 4 2055« 65
Of other anemometers, those most in use consist of
small metal vanes fixed to a horizontal axis, and
made to revolve like a wind-mill. The revolutions
are recorded very much in the same way as is seen
in the ordinary gas-meter, and from this record,
within a given time, the velocity of the wind is
ascertained. In meteorological observatories, or
where a complete register is kept of the direction and
strength of the wind, anemometers of a much more
complicated nature are employed. Of these, perhaps
the most complete is that invented by Mr Osler.
In his instrument, the force of the wind is ascer-
tained in a different way from any of those to which
we have referred. A brass plate one foot square is
suspended by means of springs, and being attached
to the vane of the instrument, is maintained at right
angles to the direction of the wind, This plate, by
the action of the wind, is beaten back upon the
springs, and in so doing, causes a pencil to move
to the south-east, is marked, even
on ordinary maps, as the scene of
numerous shipwrecks.
ANEMO'METER (Gr. anemos,
the wind, and metron, a measure ;
Fr. anémométre, Ger. Wind-
messer), an instrument for mea-
suring the strength and velocity
of the wind. Among the various
instruments which have been
z designed for this purpose, that
I invented by Dr Lind (1775 A.D.)
Dr Lind’s A, i still considered to be one of the
most convenient and accurate.
The accompanying figure gives a representation of it.
AB and CD are two upright glass tubes about 9 inches
4
backwards and forwards on a sheet of paper placed.
below it. This sheet of paper is made to pass under
the pencil in a direction at right angles to its oscilla-
tion; and by means of clock-work, moves at a uni-
form rate, so that the force of the wind at any par-
ticular time of the day is recorded with perfect
accuracy. A pencil in connection with the vane,
1AM 2
22
mwsgz
high, and % of an inch wide, connected below by a
much narrower tube, E, varying from 1%y to 5% of
an inch in width. The tube AB is bent at right
angles, so as to receive the wind blowing into it
horizontally. A scale, graduated in inches and parts
of an inch, is placed between the tubes, and the
M LNTTa ST 9 A0 AL 2
Register-sheet of an Osler’s Anemometer.
whole instrument is made to turn round the steel
and moving in the same transverse line as the
spindle, I, which can be screwed into a block of former, records the changes in the direction of the
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