MER 
nal parts, ■which we have in hooks of navi- 
gation, are made by a continual addition 
of secants; they are calculated in some 
books for every degree and minute of lati- 
tude ; and they will serve either to make or 
graduate a Mercator’s chart, or to work the 
Mercator’s sailing. To use them, you must 
enter the table with the degree of latitude 
at the head, and the minute on the first co- 
lumn towards the left hand, and in the 
angle of meeting you will have the meri- 
dional parts. Having the latitudes of two 
places, to find the meridional miles or mi- 
nutes between them, consider whether one 
of the places lies on the equator, or both 
on the same side of it, or, lastly, on dif- 
ferent sides. 1. If one of the proposed 
places lies on the equator, then the meridio- 
nal difference of latitude is the same with 
the latitude of the other place, taken from 
the table of meridional parts. % If the two 
proposed places be on the same side of the 
equator, then the meridional difference of 
latitude is found by subtracting the meri- 
dional parts answering to the least latitude, 
from those answering to the greatest, and 
the difference is that required. 3. If the 
places lie on different sides of the equator, 
then the meridional difference of latitude is 
found by adding together the meridional 
parts answering to each latitude, and the 
sum is that required. 
MERLON, in fortification, is that pai't 
of a parapet which is terminated by two 
embrasures of a battery. Its height and 
thickness is the same witli tliat of the para- 
pet ; but its breadth is generally nine feet on 
the inside, and six on the outside. It serves 
to cover those on the battery from the 
enemy ; and is better when made of earth 
well beat and close, than when built with 
stone ; because these fly about and wound 
those they should defend. 
MEROPS, in natural history, the hee~ 
eater, a genus of birds of the order Pic®. 
Generic character : bill quadrangular, some- 
what curved, compressed, and pointed ; 
nostrils small, at the base of the bill ; tongue 
slender, and in some species ciliated ; the 
outer toe somewhat connected with the 
middle one. Gmelin notices twenty-six spe- 
cies, and Latham twenty. We shall men- 
tion only M. apiaster, or the common bee- 
eater : this is about ten inches long, and 
found in many countries of Europe, though 
never observed in Great Britain. It is par- 
ticularly fond of bees, but will eat various 
other insects ; many of which it seizes ; and 
like the swallow, on the wing. When in- 
MES 
sects are witli difficulty to be found, it 
feeds on many species of seeds. In the 
markets of Italy it is frequently to be seen 
among the poulterers collections. It builds 
in the deep holes to be found on the banks 
of rivers. In the island of Candia these 
birds are often taken by boys, in the same 
manner as sw'allows, by a line, with an in- 
sect attached to a hook at the end of it. The 
cockchafer is chiefly employed for this pur- 
pose, notwithstanding its being thus fas- 
tened, it continues its flight, and is tliiis 
the most effectual of the decoys used on 
those occasions. 
MESEMBRYANTHEMUiM, in botany, 
Jig-marigold, a genus of the Icosandria Pen- 
tagynia class and order. Natural order of 
Succulent® Ficoide®, Jussieu. Essential 
character ; calyx five cleft ; petals numer- 
ous, linear ; capsule fleshy, inferior, many 
seeded. There are seventy-five species, of 
which M. nodifiorum Egyptian fig-marigold 
is a native of Egypt, where they cut up 
the plants, and burn them for pot ash : it is 
esteemed the best sort for making hard soap 
and the finer glass ; it is an annual plant, 
with diffused, decumbent stems ; calyxes 
five-toothed, two of the teeth larger, leaf 
shaped ; petals flat, narrow, connate at the 
base ; stigmas usually five. M. crystalli- 
num, diamond fig marigold, or ice plant : 
this is also an annual, distinguished by its 
leaves and stalks, being closely covered 
with pellucid pimples full of moisture, 
which, when the sun shines on them, reflect 
the light, appearing like small bubbles of 
ice, whence its name ; many call it the dia- 
mond ficoides. 
MESENTERY, a thick fat membrane, 
placed in the midst of the intestines, parti- 
cularly of the smaller ones, whence it has 
the name. 
MESPILUS, in botany, a genus of the 
Icosandria Pentagynia class and order. 
Natural order of Pomace®. Rosace®, Jus- 
sieu. Essential character ; calyx five cleft ; 
petals five ; berry inferior, five seeded. 
There are nine species, of which M. ger- 
manica, Dutch medlar ; this tree never 
rises with an upright trunk, but sends out 
crooked deformed branches, not far from 
the ground ; the leaves are large, entire, 
and downy on their under side ; flowers 
very large, as is also the fruit, which is 
rounder aiid approaches nearer to the shape 
of an apple. This tree bearing the largest 
fruit is now generally cultivated : the Not- 
tingham medlar has a more poignant taste, 
but the fruit is considerably less. 
