104 
1VT A P 
AI A R 
M A R 
by lliis means, in the line GH, you must 
transfer them from that line to t lie side lines 
AC, BD, after the following manner: 1. Set 
-one foot- of the compasses in A, and extend- 
ing the other to the first point above C, 
marked 1, transfer this distance, viz. A 1, to 
the lines AC, BD, and draw a line parallel to 
the equator AB, for the tenth -parallel 2. Next 
transfer the distance A 2 into the lines AC, 
111), from the 10th parallel to the 20th, which 
is to be drawn. 3. In the same manner the 
distances A3, A 4, A 5, &c. laid off upon the 
lines AC, BD, from the immediately preced- 
ing parallels, viz. 20, 30, 40, &c. will suc- 
cessively point out where the parallels 30, 40, 
30, Ac. are to be drawn. 
This is the geometrical projection, which 
may also be laid down by means of a scale 
or table of meridional parts, by the line of se- 
cants, &c. 
This projection supposes the earth, instead 
of a globular, to have a cylindrical ligure; 
in consequence of which, the degrees of lon- 
gitude become of an equal length throughout 
the whole surface, and are marked out on 
the map by parallel ‘lines. The circles of 
i iLitucle also are represented by lines cross- 
ing the former at right angles, but at unequal 
distances. The further we remove from the 
equator, -the longer the -degrees of latitude be- 
come in proportion to those of longitude, and 
that in no less a degree than as the secant of 
an arch to the radius of the circle; that is, if 
we make one degree of longitude atthe equator 
the radius of a circle; at one degree distant 
from the equator, a degree of latitude will be 
expressed by the -secant of one degree ; at ten 
degrees distance, by the secant of ten de- 
grees, and so on. A map of the world, there- 
fore, canud'tfce delineated upon this projection, 
without distorting the shape of the countries 
in an extraordinary manner. The projection 
itself is, however, as we have already observ- 
ed, very useful in navigation, as it shows the 
different bearings with perfect accuracy, 
which cannot be done upon any other map. 
_ We shall’ now add a more exact me- 
thod of projecting particular maps, where- 
in the squares are so projected as to form 
equal diagonals throughout. 
Of the projection of maps of particular 
parts *f the world . — -There are several me- 
thods of projecting particular parts of the 
world, we shall notice only two. First, when 
the meridians and parallels of latitude are 
right lines. 
To project a map of England after this 
method. — England is situated between 2° E. 
and 6' 20' W. from Greenwich, and between 
50° and 56° N. lat. 
Draw a base line AB, fig. 8, in the middle 
of which erect the perpendicular CD. 
Assume a distance for a degree of lat. and 
set off as many degrees on CD as are wanted, 
which in this instance are 6 ; but as a little 
space beyond the limits of the country is ge- 
nerally left, set off 7.- 
Through these points draw lines parallel to 
AB, which will be parallels of latitude. 
Respecting the degrees of longitude it must 
be observed, that on the equator they would 
be of the same length as they are on a meri- 
dian, but must gradually decrease from thence 
•to 0 at the poles. 
h followin table exhibits the length in 
g.Mgiuphical miles, of a degree of longitude 
mr ev ry degree of latitude. 
' 3 
Deg 
Lat. 
Gcograp. 
Miles. 
Deg 
.Lat. 
Gcograp. 
Miles. 
Deg. 
I Lat. 
Gcograp. 
Miles. 
0 
60/X) 
31 
51,43 
61 
£9,09 
1 
59,99 
32 
50,88 
} 62 
28,17 
2 
59 96 
33 
50,32 
I 68 
27, *24 
3 
59,92 
34 
49,74 
| 64 
26,30 
4 
59,85 
25 
49,15 
j 65 
05 
6 
5 9,77 
36 
48,54 
66 
24,41 
6 
59,67 
37 
47,92 
67 
23,4 1 
7 
59,56 
38 
47,28 
68 
22,48 
8 
59,42 
39 
46,63 
69 
21,50 
9 
59,26 
40 
45,96 
70 
20,52 
10 
59,09 
4 1 
45,28 
71 
1 9,53 
11 
58,90 
42 
44,59 
72 
18,54 
12 
58,69 
43 
43,38 
73 
17,54 
13 
58,46 
44 
43,16 
74 
16,53 
14 
58,22 
45 
42,43 
75 
15,53 
15 
57,95 
46 
41 ,68 
76 
14,52 
16 
57,67 
47 
40,92 
77 
13,50 
17 
57,38 
48 
40,15 
78 
1 2,47 
18 
57,06 
49 
39,36 
79 
1 1 ,45 
19 
56,73 
50 
31,57 
80 
10,42 
20 
56,38 
51 
38,76 
81 
9,38 
21 
56,02 
52 
36,94 
% 8 - 
8,34 
22 
55,63 
53 
36,11 
83 
7,31 
23 
55,23 
r } A 
35,27 
84 
6,27 
24 
54,31 
55 
34,41 
85 
5,23 
25 
54,38 
56 
• 33,55 
86 
4,18 
26 
53,93 
57 
32,68 
87 
3,14 
27 
53, -16 
58 
31,79 
88 
2,09 
28 
52,97 
59 
30,90 
89 
1,04 
29 
52,47 
60 
30,00 
90 
0,00 
30 
51,96 
1 
To use this table, divide the assumed de- 
gree into sixty parts by a diagonal line, tig. 9 : 
look for the number of miles answering to the 
degree of lat. 49, which is 39, 36, sav 39$, 
which take off the scale, fig. 9, at a, and set 
off four times from C towards A, and the 
same from C towards B. The top meridian 
is 56® of lat. opposite which, in t.ie table, is 
33, 55, say 33$, which take from the, scale, 
fig. 9, at I), and set olf four times from D to- 
wards E, and the same from D towards F. 
Draw the meridian lines to the -corresponding 
divisions at top and bottom, of which 0 0 is 
the meridian of London. 
Second. When the meridians and paral- 
lels are curved lines. 
To project a map of Europe by this method. 
— Draw abase line GH, fig. 10, "in the middle 
of which erect the perpendicular JP, and as- 
sume any distance for 10° of latitude. 
Europe extends from 36° to 72* N. lat. 
Let the point .1 be 30°, from which set off 
six of the assumed distances to P, which will 
be the N. pole. 
Number the distances 40, 50, 60, Ac. 
On the centre P, describe arcs passing 
through the points of division on the line JP, 
which will be parallels of latitude. 
Divide the space assumed for 10° of lat. 
into 60 parts by a diagonal line, lig. 11. 
Look into the foregoing table for the num- 
ber of miles answering toAo 0 , which is 51,96, 
say 52, which take from the scale, fig. 11, at 
b. 
Set this distance off on the arc 30, 30, 
from the centre line J P both ways. 
Do the same for 40°, 50°, 60°, &c. 
Through the corresponding divisions, on 
all the arcs, draw curve lines; which will re- 
present the meridians. 
Number the degrees of lat. and Ion., which 
will complete the diagram. 
MARANTA, Indian arrow-root, a genus 
of the monogynia order, in the monandria 
class of plants, and in the natural method 
ranking under the eighth order, scitaminese. 
The corolla is ringent and quinquetid, with 
two segments alternately patent. There arc 
live species, all of thehl herbaceous perennial 
exotics of the Indies, kept here in hot-houses 
for curiosity : they have thick, knotty., creep- 
ing loots, crowned with long, broad* arurnli- 
naceous leaves, ending in points, and upright 
■ stalks, half a yard high, terminated by bunches 
ot monopelalous, ringent, live-parted dow- 
ers. The root of the galanga is used by the 
Indians to extract the virus communicated by 
their poisoned arrows : whence it lias derived 
its name of arrow-root. The arundinacea, 
or starch plant, rises -to two feet, has broad 
pointed leaves, small white flowers, and one 
seed. It is cultivated in gardens and in pro- 
vision grounds in the West Indies ; and the 
starch is obtained from it by the following 
process: The roots when a year old are dim 
up, well washed in water, and then Ixraten in 
large deep wooden mortars to a pulp. This 
is thrown into a large tub of clean water, 
'l’he whole is then well stirred, and the fibrous 
part wrung out by the hands, and thrown 
away. The milky liquor being passed through 
a hair-sieve, or coarse cloth, is suffered to 
settle, and the clear water is drained off. At 
the bottom of the vessel is a white mass, 
which is again mixed with clean water, and 
drained: lastly, the mas* is dried on sheets 
in t he sun, and is pure starch. 
MARAT TIA, a genus of the cryptogamia 
hlic.es. The capsules are oval, gaping lonfo- 
tudinally at top, with several cells on each 
side. 'There are three foreign species. 
MARBLE, in natural history, a genus of 
fossils, composed chiefly of Time ; bein'* 
bright and beautiful stones, moderately harif, 
not giving fire with steel, fermenting with, 
and soluble in, acid menstrua, and calcining 
in a slight lire. The word comes from the 
French marbre, and that from the Latin 
marmor, of the Greek , to shine 
or glitter. See Lime. 
I he colours by which marbles are distin- 
guished are almost innumerable; but the 
most remarkable are, I. The black marble 
of Handers. 2. Plain yellow. 3. Yellow 
with some white veins. 4. Yellow with 
black dendrites. 5. Yellow with brown fi- 
gures resembling ruins. 6. Black and yel- 
low. 7. Black and while. 8. Pale yellow, 
with spots of a blackish-grey colour. 9. Yel- 
low', white, and red. 10. ‘Pale yellow. 11. 
Olive-colour, with deeper-coloured cross 
lines, and dendrites. 12. Brownish- red. 13. 
Mesh coloured and yellow. 14. Gommon 
red marble. 15. Crimson, white, and grey. 
16. Reddish-brown lumps, on a whitish 
ground. 17. Blueish-grey. 18. Snow- 
white. 
The finest: solid modern marbles are those 
of Italy, Blankenburg, France, and Handers. 
It lias also been lately discovered that very 
fine marble is contained in some of the west- 
ern islands of Scotland. Those of Germany 
Norway and Sweden, are of an inferior kind’ 
being mixed with a kind of scaly limestone- 
and even several of those above-mentioned 
are partly mixed with this substance, though 
in an inferior degree. C rousted*, however, 
mentions a new' quarry of white marble in 
Sweden, which, from the specimens he had 
seen, promised to be excellent. 
TJie specific gravity of marble is from 
