H OR 
so in proportion. Thus, if I wish to know 
what o’clock it is at. Constantinople, and 
also at Boston in North America, now it is 
eight' o’clock, A. M. here. I look to the 
gazetteer, and find Constantinople to be 
29° east of London, and Boston is 70° 30' 
west : to reduce these degrees to time, I 
29 
divide each by 15, and I find = l h 5 6 m , 
70® 30 f 
and — = 4 h 42 m ; accordingly the time 
15 
at Constantinople is l h 56 m before our time, 
and at Boston it is 4 h 42 m behind it : that is, 
at eight o’clock in London it will be 56 
minutes after nine at Constantinople, and 
at Boston it will be only 18 minutes past 
three o’clock. 
HORD, in geography, is used for a com- 
pany of wandering people, which have no 
settled habitation, but stroll about, dwelling 
in waggons or under tents, to be ready to 
shift as soon as the herbage, fruit, and the 
present province is eaten bare ; such are se- 
veral tribes of the Tartars, particularly those 
who inhabit beyond the Wolga, in the king- 
doms of Astracan and Bulgaria. A hord 
consists of fifty or sixty tents, ranged in a 
circle, leaving an open place in the middle. 
The inhabitants of each hord usually form a 
military company or troop, the eldest where- 
of is commonly the captain, and depends 
on the general or prince of the whole na- 
tion. 
KORDETJM, in botany, barley, a genus 
of the "Triandria Digynia class and order. 
Natural order of Grasses. Essential cha- 
racter : calyx lateral, two-valved, one-flow- 
ered, by threes, at each toothlet of the ra~ 
chis. There are nine species. 
HORIZON, in astronomy and geogra- 
phy, that great circle which divides the hea- 
vens and the earth into two equal parts, or 
hemispheres, distinguishing the upper from 
the lower. The horizon is either sensible 
or rational : the sensible horizon is that cir- 
cle which, being discovered by our senses, 
limits our prospect. 
When we are on terra firma, this circle 
commonly seems rugged and irregular, oc- 
casioned by the unevenness of the ground ; 
but at sea, there are no such irregularities. 
The semi-diameter of this circle varieth ac- 
cording to the height of the eye of the ob- 
server. If a man, six feet high, stood upon 
a large plain, or the surface of the sea, he 
could not see quite three miles round. To 
find the distance to which a person can see, 
at any given height of the eye, or the ex- 
tent of the visible horizon, is a problem of 
H O R 
some Utility, particularly to mariners : the 
rule is, “ multiply the square root of the 
height of the eye'in feet, by 1.225, and the 
product is the distance in miles, to which 
we can see from that height thus a sailor, 
standing at the top-mast of a ship 120 feet 
high, can see a distance in miles — y^l20 
X 1.225 = 13.45 = to 13 miles and a half 
nearly. 
The rational, or true horizon, is a great 
circle of the apparent celestial sphere, di- 
viding it into two equal hemispheres, and 
serving as the limits of elevation or depres- 
sion of celestial objects. This horizon be- 
ing parallel to the sensible horizon, ’ is dis- 
tant from it by the semi-diameter of the 
earth, through whose centre it passes : for 
the astronomers reduce the appearances of 
the heavens to a spherical surface, which is 
not concentrical to the eye, but to the 
earth. It divides the heaven and earth into 
two parts, the one light, and the other dark, 
which are greater or lesser, according to 
the condition of the place, &c. It deter- 
mines the rising and setting of the sun, 
moon, or stars, in any particular latitude ; 
for, when any of these appear just at the 
eastern part of th* horizon, we say, it rises; 
and when it does so at the western part, we 
say, it sets. And from hence also the alti- 
tude of the sun or stars is accounted, which 
is their height above the horizon. This cir- 
cle is divided by astronomers into four quad- 
rants, or cardinal points. The poles of 
this horizon are the zenith and the nadir : 
and the innumerable circles drawn through 
these poles to the horizon, are called the 
vertical circles, or azimuths. These two 
horizons produced to the fixed stars, will 
appear to coincide into one, since the earth, 
compared to the sphere in which the fixed 
stars appear, is but a point; therefore the 
two circles, which are but a point distant 
from each other, may be well considered as 
coinciding into one. 
Horizon of a globe. See Globe. 
HORIZONTAL, something relating to 
the horizon; or that is taker in, or on a le- 
vel with the horizon : thus we say, an hori- 
zontal plane, &c. 
It frequently happens at sea, that the at- 
mosphere is so hazy as to prevent a distinct 
view of the horizon, which is a great hin- 
drance to accurate observations. This in- 
convenience is remedied by an 
Horizontal speculum, which consists in 
a well-polished metal speculum, about three 
or four inches in diameter, inclosed within 
a rim of brass; so fitted, that the centre 
