356 ASTRO 
firft who gave an account of the circumference of the fea 
and land ; and it feenis his meafure was ufed by the fuc- 
ceeding mathematicians, till the time of Eratofthenes. 
Ariftotle, at the end of lib. ii. de Coe lo, fays, that mathe¬ 
maticians who have attempted to meafure the circuit of 
the Earth, make it 40,000 (tadiums : which it is thought is 
the number determined by Anaximander. 
Eratofthenes, who lived about 200 years before Chrift, 
was the next who undertook this bulinefs ; which, as Cleo- 
inedes relates, he performed by taking the Sun’s zenith 
diftances, and meafuring the diftance between two places 
under the fame meridian; by which he deduced for the 
whole circuit about 250,000 Radiums, which Pliny ftates at 
31,500 Roman miles, reckoning each at 1000 paces. But 
this meafure was accounted falfe by many of the ancient 
mathematicians, and particularly by Hipparchus, who li¬ 
ved 100 years afterwards, and who added 25000 ftadiums 
to the circuit of Eratofthenes. 
Poffidonius, in the time of Cicero and Pompey the Great, 
next meafured the Earth, viz. by means of the altitudes of 
a ftar, and meafuring a part of a meridian; and he con¬ 
cluded the circumference at 240,000 ftadiums according 
to Cleomedes, but only at 180,000 according to Strabo. 
Ptolemy, in his Geography, (ays, that Marinos, a celebra¬ 
ted geographer, attempted fomething of the fame kind; 
and, in lib. i. cap. 3, he mentions, that he himfelf had tried 
to perform the bulinefs in a way different from any other 
before him, which was by means of places under-different 
meridians: but he does not fay how much lie made, the 
number; for he (fill made ufe of the 180,000, which had 
been found out before him. 
Snellius relates, from the Arabian geographer Abelfe- 
dea, who lived about the 1300th year of Chriff, that about 
the Sooth year of Chrift, Almaimon, an Arabian king, 
having colleited together fome (kilt'ul mathematicians, 
commanded them to find out the circumference of the 
Earth. Accordingly thefe made choice of the fields of 
Mefopotamia, where they meafured under the fame me¬ 
ridian from north to fouth, till the pole was deprefled one 
degree lower: which meafure they found equal to fifty-fix 
miles, or fifty-fix and a half: fo that according to them 
the circuit of the Earth is 20,160 or 20,340 miles. 
It was a long time after this before any more attempts 
were made in this bufinefs. At length, however, the lame 
Snell, above-mentioned, profeffor of mathematics at Ley¬ 
den, about the year 1620, with great fkili and labour, by 
meafuring large diftances between two parallels, found one 
degree equal to 28,500 perches, each of which is twelve 
Rhinland feet, amounting to nineteen Dutch miles, and 
fo the whole periphery 6840 miles; a mile being, accord¬ 
ing to him, 1500 perches, or 18,000 Rhinland feet. See 
Tiis treatife called Eratofthenes Batavus. 
The next that undertook this meafurement, was Rich. 
Norwood, who, in the year 1635, by meafuring the diftance 
from London to York with a chain, and taking the Sun’s 
meridian altitude, June 11, old ftyle, with a (extant of 
■about five feet radius, found a degree contained 367,20,0 
feet, or (ixty-nme miles and a half and fourteen poles; 
and thence the circumference of a great circle of the Earth 
is a little more than 25,036 miles, and the diameter a lit¬ 
tle more than 7966 miles. 
The meafurement of the Earth by Snell, though very 
ingenious and troublefome, and much more accurate than 
any of the ancients, being ftill thought by fome French 
mathematicians as liable tocertain fmall errors, the bufinefs 
was renewed, after Snell’s manner, by Picard and other 
mathematicians, by the king’s command ; ufing a quadrant 
of 3-5- French feet radius; by which they found a degree 
contained 342,360 French feet. M. Caflini the younger, 
in the year 1700, by the king’s command alfo, renewed 
the bufinefs with a quadrant of ten feet radius, for taking 
the latitude, and another of 3^ feet for taking the angles of 
the triangles; and found a degree, from his calculation, 
contained 57,292 toifes, or almoft fixty-nine Engliih miles 
N O M Y. 
and a half. From the mean of all which, the following 
dimenfions of the Earth may be taken as near the truth: 
The circumference 25,000 miles. 
The diameter 79573 - miles, 
The fuperfices 198,944,206 fquare miles, 
The folidity 263,930,000,000 cubic miles. 
Alfo the feas and unknown.parts of the Earth, by a mea¬ 
furement of the beft maps, contain 160,522,026 fquare 
miles; the inhabited parts, 38,922,180: of which Europe 
contains 4,456,065 ; Afia, 10,768,823 ; Africa, 9,654,807 ; 
and America, 14,110,874 fquare miles. 
The fubftance or body of the Earth is diftinguilhed into 
three parts or regions, viz ift, The external part or cruft, 
being that from which vegetables fpring and animals are 
nurfed. 2d, The middle, or intermediate parr, which is 
poffcfled by foffils, extending farther than human labour 
ever yet penetrated. 3d*, The internal or central part, 
which is utterly unknown to us, though by many authors 
fuppofed of a magnetic nature; by others, a mafs or fphere 
of fire ; by others, an abyfs or collection of waters, fur- 
rounded by the ftrata of Earth; and by others, a hollow 
empty fpace, inhabited by animals, who have their Sun, 
Moon, planets, and other conveniences, within the fame. 
But others divide the body of the globe into two parts, 
viz. the external part, called the cortex, including the in¬ 
ternal, which they call the nucleus, being of a different 
nature from the former, and poffeffed by fire, water, or 
more probably by a conliderable portion of metals, as it 
has been found, by calculation, that the mean denfity of 
the whole Earth is near double the denfity of comraon- 
ftone. The external part of the globe either exhibits in¬ 
equalities, as mountains and valleys; or it is plane and le¬ 
vel ; or dug in channels, fiffures, beds, &c. for rivers, 
lakes, feas, &c. Thefe inequalities in the face of the 
Earth mod naturalifts fuppofe have arifen from a rupture 
or fubverfion of the Earth, by the force either of the fub- 
terraneous fires or waters. The Earth, in its natural and 
original date, it has been fuppofed by Des Cartes, and 
after him Burnet, Steno, Woodward, Whifton, and others, 
was perfectly round, fmooth, and equable; and they ac¬ 
count for its prefent rude and irregular form, principally 
from the great deluge. 
In the external or cortical part of the Earth, there ap¬ 
pear various ftrata, fuppofed the fediments of feveral 
floods; the waters of which, being replete with matters 
of divers kinds, as they dried up, or oozed through, de- 
pofited thefe different matters, which in time hardened in¬ 
to ftrata of done, fand, coal, clay, &c. Dr. Woodward 
has confidered the circumftances of thefe ftrata with great 
attention, viz. their order, number, fituation with refpedt 
to the horizon, depth, interfeftions, fiffures, colour, con¬ 
fidence, See. He aferibes the origin and formationof them 
all, to the great flood or cataclyfmus. At that terrible 
revolution he fuppofed that all forts of terreftrial bodies 
had been diflolved and mixed with the waters, forming all 
together a chaos or confufed mafs. This mafs of terref¬ 
trial particles, intermixed with water, he fuppofes was at 
length precipitated to the bottom ; and that generally, ac¬ 
cording to the order of gravity, the heavieft linking firft, 
and the lighted: afterwards. By fuel) means were the ftra¬ 
ta formed of which the Earth confifts; which, attaining 
their folidity and hardnefs by degrees, have continued fo 
ever fince. Thefe fediments, he farther concludes, were 
at firft all parallel and concentrical; and the furfaceof the 
E'arth, formed of them, perfectly fmooth and regular; but, 
that, in courfe of time, divers changes happening, from 
earthquakes, volcanoes, &c. the order and regularity of 
the ftrata were difturbed and broken, and the furface of the 
Eartli by fuch means brought to the irregular form in 
which it now appears. 
M. de Buffon furmifes that the Earth, as well as the 
other planets, are parts (truck off from the body of the 
Sun by the collifion of comets; and that, when the Earth 
affumed 
