3 $4 A S T R O 
ed, as may be feen under the article Astro log y. The 
common opinion is, that the Lunar influence is chiefly 
exerted about the time of the full and change, but more 
efpecially the latter ; and it would feern that long experi¬ 
ence has in home degree eftablifhed the fact : hence, per- 
fons obferved at thole times to be a little deranged in their 
intellects, are called Lunatics; and hence many perfons 
anxioufly look for the new Moon to bring a change in the 
weather. The Moon’s influence on the i'ea, in producing 
tides, being agreed upon on all hands, it is argued that fhe 
mud alfo produce fimilar changes in the atmofphere, but 
in a much higher degree ; which changes and commotions 
there, mull, it is inferred, have a confiderable influence 
on the weather, and on the human body. 
Befldes the obfervations of the ancients, which tend to 
efiabliih this doClrine, feveral among the modern philo¬ 
sophers have defended the fame opinion, and that upon 
the ftrer.gth of experience and observation ; while others 
as ftrenuoufly deny the fait. The celebrated Dr. Mead 
was a believer in the influence of the Sun and.Moon on 
the human body, and he publifhcd a book to this purpofe, 
intitled, De Imperio Solis ac Lunas in Corpore Humano. 
The exiftence of fitch influence is however oppofed by 
Dr. Horlley, bilhop of Rochefler, in a learned paper upon 
this fubjeCf in the Philof. TranL for the year 1775 ; where 
he gives a fpecimen of arranging tables of meteorological 
obfervations, fo as (o deduce from them faCts, that may 
either confirm or refute this popular opinion ; recommend¬ 
ing it to the learned, to collect a large feries of fuch ob¬ 
fervations, as no conclufions can be drawn from one or 
two only. Gn tlte other hand, profelfor Toaldo, and fome 
French philofophers, take the oppofite fide of the queftion ; 
and, from the authority of a long feries of obfervations, 
pronounce decidedly in favour of the Lunar influence. 
Of. MARS. 
Mars is the leaft bright and elegant of all the planets; 
its orbit lies between thole of the Earth and Jupiter, but 
very diftant from both. He appears of a fiery reddiflt hue ; 
and, from the duikinefs of his appearance, many have con¬ 
jectured that he is encompafled with a thick cloudy atmof¬ 
phere ; his light is by no means fo bright as that of Venus, 
though he fometimes appears nearly equal to her in fize. 
He is denoted by this character being the mark for 
iron, rudely formed from a man holding a fpear protruded, 
reprefenting the god of war of the fame name. 
The mean diftance of Mars from the Sun, is 1524 of 
thofe parts, of which the diflatice of the Earth from the 
Sun is ;ooo ; his eccentricity 141 ; and his real dillance 
145 millions of miles. The inclination of his orbit to the 
plane of the ecliptic, is i° 52' ; the length of his year, or 
the period of one revolution about the Sun, is 686-|| of 
bur days, or 667a of his own days, which are forty mi¬ 
nutes longer than ours, the revolution on his axis being 
performed in 24I1. 40'. He moves at the rate of 55,287 
smiles per hour. His mean diameter is 4444 miles ; and the 
fame ieen from tiie Sun is n n : the place of the aphelion 
is rij 32'; place of his afeending node ft 17 0 17'; and 
his parallax, according to Dr. Hook and Mr. Flamfleed, 
is fcarce 30". 
Galileo firAdifcovered the phafes of Mars; after which, 
fome Italians, in 1636, had an imperfeCt view ef a fpot. 
But in 3666, Dr>. Hook and M. Caffini difeovered fome 
v eil-defined fpots ; and the latter determined the time of 
its rotation to be 24b. 40'. Soon after, M. Maraldi ob¬ 
ferved fome fpots, and determined the time of rotation to 
be 24I1. 39'. H: alfo obferved a very bright part near the 
fouthern pole, appearing like a polar zone ; this, he fays, 
has been obferved for fixty years ; it is not of equal bright- 
nefs, more than one half of it being brighter titan the reft; 
and titat part which is lead bright, is fubjeCt to great 
changes, and has fometims difappeared- Something like 
this has been feen about the north pole. The rotation is 
made according to the order of the figns. Dr. Herfchel 
makes the time of aftderial revolution to be 24ft. 39', 2 
N O M Y. 
without the probability of a greater error than 2’34". Hs 
propofes to find the time of a liderial revolution of Mars, 
in order to difeover, by future obfervations, whether 
there is any alteration in the time of the revolution of the 
Earth, or of the planets, about their axes ; for a change 
of either would thus be difeovered. He chofe Mars, be- 
caufe its fpots are permanent. From farther obfervations 
upon Mars, which he publilhed in 1784, he makes its axis 
to be inclined to the eliptic 59 0 42', and 6i° 1 S' to its or¬ 
bit ; and the north pole to be directed to 17 0 47' of Pifces 
upon the ecliptic,.and 19 0 28' on its orbit. He makes the 
ratio of the diameters of Mars to be as 16 to 15. Dr, 
Malkelyne however,, has carefully obferved Mars at the 
time of oppofition, but could not perceive any difference 
in its diameters. In the acronical rifing of this planet, or 
when in oppofition to the Sun, it is five times nearer to us 
than when in conjunction with him ;. and hence appears 
much larger and brighter than at other times. 
Mars, having his light from the Sun, and revolving 
round it, has an increafe and decreafe like the Moon : it 
may alfo be obferved almoff bifeCted, when in the quadra¬ 
tures, or in perigaeon ; but is never feen cornicular, as 
the inferior planets. All which (hews both that his orbit 
includes that of the Earth within it, and that he fnines 
not by his own light. 
The analogy between Mars and the Earth is by far the 
greateft in the whole-folar fyftem ; their diurnal motion is 
nearly the fame ; the obliquities of their refpeftive eclip¬ 
tics not very different. Of all the fuperior planets, there¬ 
fore, Mars is by far neareft like the Earth ; nor w ill the 
Martial year appear fo diffimilar to ours, when we com¬ 
pare it with the long duration of the years of Jupiter, Sa¬ 
turn, and the Georgium Sidus. It probably has a con¬ 
fiderable atmofphere; for belides the permanent fpots on 
its furface, Dr. Herfchel has often perceived occafional 
changes of partial bright belts, and alfo once a darkifh one 
in a pretty high latitude ; alterations vvhich we can attri¬ 
bute to no other, caufe than the variable difpofition of 
clouds and vapours floating in the atmofphere of the pla¬ 
net. A fpedlator in Mars, will rarely, if ever, fee Mer¬ 
cury, except when he fees it palling over the Sun’s difk. 
Venus will appear to him at about the fame diftance from 
the Sun, as Mercury appears to us. The Earth will ap¬ 
pear about the fize of Venus, and never above forty-eight 
degrees from the Sun; and will be, by turns, a morning 
and evening flar to the inhabitants of Mars. 
Of JUPITER. 
Jupiter, the thunderer, or chief of ;the ancient gods, is- 
marked TJ, to reprefent the thunder-bolts, denoting the 
fame as tin, from his pure white brightnefs. He is fitu- 
ated high in the fyftem, revolving round the Sun between 
Mars and Saturn. It is the largeft of all the planets, and 
eafily diftinguifhed from them by his peculiar magnitude 
and light. His diameter is more than ten times the diame¬ 
ter of the Earth, and his magnitude is more than a thou* 
fand times. His annual revolution about the. Sun is per¬ 
formed in uy. 3i4d. i2h. 20'. 9". going at the rate of 
more than 25,000 miles per hour ; and he revolves about 
his own axis, by which his equatorial parts are. carried 
round at the amazing rate of 26,000 miles per hour, which 
is about twenty-five times fafter than the like parts of our 
Earth revolve. 
Jupiter is furrounded by faint fubftances, called zones 
or belts, in which fa many changes appear,- that they are 
generally aferibed to clouds: for fome of them have been 
firft interrupted and broken, and then have vanifhed en¬ 
tirely. They have fometimes been obferved of different 
breadths, and afterwards have all become nearly of the 
fame breadth. Large fpots have been feen in thefe belts ; 
and, when a belt vaniflies, the contiguous fpots difappear 
with it. The broken ends of fome belts have often, been 
obferved to revolve in the fame time with the fpots : only 
thofe nearer the equator in fomewhat lefs time than thofe 
nearer the poles; perhaps on account of the Sun’s greater 
f heat 
