1 62 
M E R 
greatest, and the difference is that required. 
3. It the places lie on different sides of the 
equator, then the meridional difference of la- 
titude is found by adding together the me- 
ridional parts answering to each latitude, aid 
the sum is that required. 
To Jlnd the Meridional Parts to any Spheroid, 
•with the same exactness as in a Sphere. Let the semi- 
diameter of the equator be to the distance of 
the centre from the focus of the generating el- 
lipse, as m to 1. Let A represent the latitude 
for which the meridional parts are required, s 
the sine of the latitude, to the radius 1 : iind the 
arc B, whose sine is take the logarithmic 
m 
tangent of half the complement of B, from the 
common tables ; subtract the log. tangent from 
10.0000000, or the log. tangent ©f 45 ' ; multi- 
ply the remainder by tire number 7915.7044679, 
and divide the product by m ; then the quotient 
subtracted from the meridional parts in the 
sphere, computed in the usual manner for the 
latitude A, will give the meridional parts, ex- 
pressed in minutes, for the same latitude in the 
spheroid, when it is the oblate one. 
Example. If mm * 1 * * 1000 ’ 22, then the 
greatest difference of the meridional parts in 
the sphere and spheroid is 76.0929 minutes. In 
other cases it is found by multiplying the re- 
mainder above-mentioned by tire number 
1174.078. 
When the spheroid is oblong, the difference 
in the meridional parts between the sphere and 
spheroid, for the same latitude, is then deter- 
mined by a circular arc. 
We shall here add a table of meridional parts, 
calculated both for the sphere and oblate sphe- 
roid, by the reverend Mr. Murdoch, in his new 
and learned Treatise of Mercator’s Sailing ap- 
plied to the true Figure of the Earth. By this 
table may be projected a true chart for any 
art of the earth’s surface, and the several pro- 
lems of sailing may he solved by it. Maps of 
countries may be delineated and applied to the 
various purposes of navigation, geography, and 
astronomy. Nor are the errors of the common 
spherical projections so very small in many 
cases, as to be inconsiderable and not danger- 
©us. For instance, if a ship sails from south la- 
titude 25°, to north latitude 30 n , and the angle 
©f the course be 43 s ; then the difference of lon- 
gitude by the common table would be 3206'\ 
exceeding the true difference 314 V by 65 or 
miles. Also the distance sailed would be 4512, 
exceeding the true distance, 4423, by 89', or 
miles ; which differences are too great to be neg- 
lepted. For other instances of such a correction 
of the charts, we refer to the author’s admi- 
rable book above-mentioned. 
A TABLE 
Cf Meridional Parts to the Spheroid and Sphere, 
with their Differences. 
B. 
Spheroid. 
Sphere. 
Biff. 
1 
53.7 
60.0 
1. S 
S 
117.3 
120.0 
2. 7 
3 
176.1 
180.1 
4. 0 
4 
234.9 
210 2 
5. 3 
5 
293.8 
300.4 
6. « 
6 
352.7 
360.6 
7. 9 
7 
411.8 
421.0 
9. 2 
8 
471.0 
481.5 
10. 5 
9 
530.4 
542.2 
11. 8 
iO 
589.9 
603.0 
13. 1 
11 
649.7 
664.1 
14. 4 
12 
709.6 
725.3 
15. 7 
\3 
769.8 
786. S 
17. 0 
14 
830.2 
848.5 
18. 3 
15 
890.9 
910.5 
19. 6 
16 
951.8 
972.7 
20. 9 
17 
1013.1 
1035.3, 
22. 2 
M E R 
TABLE ( continued ), 
B. 
Spheroid. 
Sphere. 
Diff. 
18 
1074.8 
1098 3 
23. 5 
19 
1136.8 
1161.6 
24. 8 
20 
1199.2 
1225.2 
26. 0 
21 
1262.0 
1289.2 
27. 2 
22 
1325.3 
1353.7 
28. 4 
23 
1389.0 
1418.6 
29. 6 
24 
1453.3 
1484.1 
30. 8 
25 
1518.0 
1550.0 
S2. 0 
26 
1583.3 
1616.5 
S3. 2 
27 
1649.1 
1683.5 
34. 4 
28 
1715.6 
1751.2 
35. 6 
29 
1782.7 
1819.5 
36. 8 
30 
1850.5 
1888.4 
37. 9 
31 
1919.0 
1958.0 
39. 0 
32 
1988.2 
2028.3 
40. 1 
33 
2058.3 
2099.5 
41. 2 
34 
2129.0 
2171.4 
42. 3 
35 
2200.8 
2244.2 
43. 4 
36 
2273.4 
2317.9 
44. 5 
37 
2347.0 
2392.6 
45. 6 
38 
2421.6 
2468.3 
46. 7 
39 
2497.2 
2544.9 
47. 7 
40 
2573.9 
2622.6 
48. 7 
41 
2651.8 
2701.5 
49. 7 
42 
2730.9 
2781.6 
50. 7 
43 
281,1.3 
2863.0 
51. 7 
44 
2893.1 
2945.8 
52. 7 
45 
2976.2 
3029.9 
53. 7 
46 
3060.9 
3115.5 
54. 6 
47 
3147.2 
3202.7 
55. 5 
48 
3235.1 
3291.5 
56. 4 
49 
3324.8 
3382.1 
57. 3 
50 
S416.S 
3474.5 
58. 2 
51 
3509.7 
3568.8 
59. 1 
52 
3605.3 
3665.2 
59. 9 
53 
3703.1 
3763.8 
60. 7 
54 
3803.1 
3864.6 
61. 5 
55 
3905.7 
3968.0 
62. 3- 
56 
4010.9 
4073.9 
63. 0 
57 
4118.9 
4182.6 
63. 7 
58 
4229.8 
4294.2 
64. 4 
59 
4344.0 
4409.1 
65. 1 
60 
4461.5 
4527.3 
65. 8 
61 
4582.7 
4649.2 
66. 5 
62 
4707.8 
4775.0 
67. 2 
63 
4837.1 
4904.9 
67. 8 
64 
4971.0 
5039.4 
68. 4 
65 
5109.8 
5178.8 
69. 0 
66 
5254.0 
5323.6 
69. 6 
67 
5403.9 
5474.0 
70. 1 
68 
5560.2 
5630.8 
70. 6 
69 
5723.5 
5794.6 
71. 1 
70 
5894.4 
5965.9 
71. 5 
71 
6073-7 
6145.6 
71. 9 
72 
6262.4 
6334.7 
72. 3 
72 
6461.6 
6534.3 
72. 7 
74 
6672.6 
6745.7 
73. 1 
75 
6896.3 
6970 3 
73. 5 
76 
7136.2 
7210.0 
73. 1 
77 
7393.0 
7467.1 
74. 1 
78 
7670.1 
7744.5 
74. 4 
79 
7970.9 
8045.6 
74. 7 
80 
8300.2 
8375.2 
75. 0 
81 
8663.8 
8739.0 
75. 2 
82 
9070.0 
9145.4 
75. 4 
83 
9530.2 
9605.8 
75. 6 
84 
10061.1 
10136.9 
75. 8 
85 
10688.7 
10764.6 
75. 9 
86 
11456 5 
11532.5 
76. 0 
87 
12446.0 
12522.1 
76. 1 
88 
13840.4 
13916.4 
76. 0 
89 
16*23.8 
16299.5 
75. 7 
90 
1 
37.75 
MERLIN. See Falcon. 
MERLON, in fortification, is that part of 
a parapet which is terminated by two embra- 
sures of a battery. Its height and thickness 
are the same with those of the parapet; but its 
breadth is generally nine feet on the inside, 
•M E S 
and six on the outside. It serves to cover' 
those on the battery from the euemv ; and is- 
better when made of earth well beaten and- 
close, than when built with stones; because 
they fly about and wound those they should 
defend. 
. MEROPS, in ornithology, a genus belong- 
ing to the order of picre. The bill is crook- 
ed, flat, and carinated ; the tongue is jagged 
at the point; and the feet are of the walking 
kind. The principal species are, 1. The 
apiaster, or bee-eater, which has an iron-co- 
loured back; the belly and tail are of a blem- 
ish green; and the throat yellow. This bird 
inhabits various parts of Europe, on the conti- 
nent, though notin England; yetis said to have 
been seen in Sweden, ami flocks of them have 
oecn met with at Anspach in (Germany in the 
month of June. It takes the name of bee- 
eater from its being very fond of those in- 
sects; but, besides these, it will catch gnats, 
fiies, cicadae, and other insects, on the wing, 
like swallows. . r I hese birds make their nests 
in the holes in the banks of rivers, like the 
sand martin and kingsfisher; at the end of 
which the female lays from five to seven 
white eggs, rather less than those of a black- 
birth I he nest itself is composed of moss. 
2. The viridis, or Indian bee-eater, is green, 
with a black belt on the breast; and thp 
throat and tail are black. It inhabits Bengal. 
3. The erythropterus, or red-winged bee- 
eater, is in" length six inches; the bill is one 
inch, and black; the upper parts of the head, 
body, wings, and tail-coverts, are green 
brown, deepest on the head and back, lightest 
on J;he rump and tail-coverts ; behind the eve 
is a spot of the same, but of a very deep co- 
lour; the quills and tail are red, tipped with 
black; the last two inches in length; the 
throat is yellow ; the under parts of the body 
are a dirty white ; and the legs black. There 
are more than 20 other species. 
M ES EM BR Y AN 111 EM U M, fig-mari- 
go'd, a genus of the pentagynia order, in the 
icosandria class of plants, and in the natural 
method ranking under the 13th order, succu- 
lente. 1 he calyx is quinquehd ; the petals 
are numerous and linear; the capsule is 
fleshy, inferior, and monospermous. There are 
seventy-five species, all African plants, from, 
the Cape of Good Hope, near 4-0 of which 
are retained in our gardens for variety. Of 
these only one is annual, and the most re- 
markable of them all : it is cdfed the crystal- 
linum, diamond, ficoides, or ice-plant. This 
singular and curious plant, being ciose’y co- 
vered with large pellucid pimples, full of 
moisture, shining brilliantly like diamonds, is 
in great esteem. It is a very tender plant 
while young, and is raised annually from seed 
by means of hotbeds. In June’ it will endure 
the open air till October, when it perishes; 
but it placed in a hot-house in autumn it will 
often live all winter. 
The other species are most durable in stem 
and foliage. Some are shrubby ; others pen- 
dulous, with loose straggling stems, and 
branches inclining to the ground ; while others, 
have no stalks at all; their leaves are univer- 
sally very thick, succulent, fleshy, and of 
many various shapes, situations, and direc- 
tions ; white some are punctured, or dotted 
With transparent points ; and some have pel- 
lucid pimples, as already mentioned. They 
afford a very agreeable variety at all times ot 
the year, and merit a place in every coltee- 
