astrongm y. 
arc eonftantly Changing, becaufe the nodes go backward 
through the whole ecliptic in eighteen years and 215 days. 
This revolution of the nodes will caufe the harvelt-moons 
to go through a whole courle of the mojl and kaji benefi¬ 
cial ftates, with refpeCt to the harveft, every nineteen years. 
Of the Horizontal Moon. 
The phenomenon of the horizontal moon is this, that it 
appears larger in the horizon than in the meridian ; where¬ 
as, from its being nearer to us in the latter cafe than in 
the former, it fubtends a greater angle. Gaffendus thought 
that, as the Moon was lefs bright hi the horizon, we look¬ 
ed at it there with a greater pupil of the eye, and there¬ 
fore it appeared larger. But this is contrary to the prin¬ 
ciples of optics, the image of an objeCt upon the retina 
not depending upon the pupil. This opinion was fupport- 
ed by a French abbe, who fuppofed that the opening of 
the pupil made the cryftalline humour flatter, and the eye 
longer, and thereby increafed the image. But there is no 
■connection between the mufcles of the iris and the other 
parts of the eye, to produce thefe effects. Des Cartes 
thought, that the Moon appeared larged in the horizon, 
becaufe, when comparing its didance with the intermedi¬ 
ate objects, it appeared then farthefl off; and, as we judge 
its didance greated in that fituation, we of courfe think it 
larger, fuppofing that it fubtends the fame angle. This 
opinion was fupported by Dr. Wallis in the Phil. Tranf. 
Mo. clxxxvii. Dr. Berkley accounts for it thus : Faint¬ 
nefs fuggeds the idea of greater didance; the Moon ap¬ 
pearing mod faint in the horizon, fuggeds the idea of great¬ 
er didance, and, fuppofing the vifual angle the fame, that 
mud fugged the idea of a greater tangible objeCt. lie 
•does not fuppole the vifible extenfion to be greater, but 
that the idea of a greater tangible extenfion is fuggeded, 
by the alteration of the appearance of the vilible exten¬ 
fion. He fays, r. That which fuggeds the idea of great¬ 
er magnitude mud be fomething perceived ; for what is 
not perceived can produce no effeCt. 2. It mud be fome¬ 
thing which is variable, becaufe the Moon does not always 
appear of the fame magnitude in thehorizon. 3. It can¬ 
not lie in the intermediate objects, they remaining the 
fame; alfo, when thefe objects are excluded from fight, it 
makes no alteration. 4. It cannot be the vifible magni¬ 
tude, becaufe that is lead in the horizon ; the caufe there¬ 
fore mud lie in the vilible appearance, which proceeds 
from the greater paucity of rays coming to the eye, pro¬ 
ducing faintnefs. Mr. Rowning fuppofes, that the Moon 
appears farthed from ns in the horizon, becaufe the por¬ 
tion of the fky, which we fee, appears, not an entire he- 
mifphere, but only a portion of one; and, in confequence 
of this, w ; e judge the Moon to be farthed from us in the 
horizon, and therefore to be then larged. Dr. Smith, in 
ieis Optics, gives the fame reafon. He makes the appa¬ 
rent didance in the horizon to be to that in the zenith as 
10 to 3, and therefore the apparent diameters in that ratio. 
The fame circumdance alfo takes place in the Sun, which 
appears much larger in the horizon than in the zenith. 
Alfo, if we take two liars near each other in the horizon, 
and two other liars near the zenith at tile fame angular 
diltance from each other, the two former will appear at a 
much greater didance from each other than the two latter. 
Upon this account, people are in general very much de¬ 
ceived in edimating the altitudes of the heavenly bodies 
above the horizon, judging them to be much greater than 
they are. Dr. Smith found, that, when a body was about 
23 0 above the horizon, it appeared to be half-way between 
the zenith and horizon, and therefore at that real altitude 
it would be edimated to be 45 0 high. Upon the fame 
principle, the lower part of a rainbow appears broader 
than the upper part. And this may be confidered as an 
argument that the phenomenon cannot depend entirely up¬ 
on the greater degree of faintnefs in the object when in the 
horizon, becaufe the lower part of the bow frequently ap¬ 
pears brighter than the upper part, at the fame time-that 
it appears larger; alfo this-caufe could have no effect up¬ 
on the didance of the dnrs; and, as the difference' of the 
apparent didance of two (far;, whofe angular didance is 
the fame, in the horizon and zenith, feents to be fully 
fufficient to account for the apparent variation of the 
Moon’s diameter in thefe lunations, it may be doubtful, 
whether the faintnefs of the object enters into any part of 
the caufe. 
With refpeCt to the nature and conftruclion of the Moon, 
and the probability of its being inhabited. Dr. Herfcht !, 
in his papers publifhed in the Philofophical TranfaCtions 
of 1795, concludes as follows: “ The Moon is a fecond- 
ary planet, the furface of which is diveriilred, like that of 
the Karth, by mountains and vallies. Its fituation, with 
refpeCt to the Sun, is much like that of the Earth ; and, 
by a rotation on its axis, it enjbys an agreeable variety of 
feafons, and of day and night. To the Moon, our globe 
will appear to be a very capital fatellite; undergoing the 
fame regular changes of illuminations as the Moon does to 
the Earth. The Sun, the planets, and the dai ry conftel- 
lations of the heavens, will rife and fet as they do here ; 
and heavy bodies will fall on the Moon as they do on the 
Earth. There feems only to be wanting, in order to com¬ 
plete the analogy, that it fliould be inhabited like the Earth. 
% ‘ To this it may be objected, that w e perceive no large 
Teas in the Mocn; that its atmofphere (the exidence of 
which has even been doubted by many) is extremely rare, 
.and unfit for the purpofes of animal life ; that its climates, 
its feafons, and the length of its days, totally differ from 
ours; that without denfe clouds (which the Moon has 
not) there can be no rain; perhaps no rivers, no lakes. 
In fliort, that, notwithdanding the fimilarity which has 
been pointed out, there feems to be a decided difference 
in the-two planets w'e have compared. My anfwer to this 
will be, that that very difference which is now objected 
will rather drengthen the force of my argument than leff- 
en its value : we find, even upon our globe, that there is 
the mod driking difference in the fituation of the creatures 
that live upon it. While man walks upon the ground, the 
birds fly in the air, and fifiies fvvim in water; %ve can cer¬ 
tainly not object to the conveniences afforded by the Moon, 
if thofe that are to inhabit its regions are fitted to their 
conditions as well as we on this globe are to ours. Anab- 
folute or total famenels feems rather to denote imperfec¬ 
tions, fuch as nature never expoles to ottr view j and, on 
this account, I believe the analogies that have been men¬ 
tioned fully fufficient to edablifh the high probability of 
the Moon’s being inhabited like the Earth. 
“ To proceed, we will now fiippofean inhabitant of the 
Moon, who has not properly confidered fuch analogical 
reafonings as might induce him to furmife that our Earth 
is inhabited, were to give it as his opinion, that the ufe of 
that great body, which he fees in his neighbourhood, is to 
carry about his little globe, that it may be properly expo- 
fed to the light of the Sun, fo as to enjoy an agreeable 
and iifeful variety of illumination, as well as to give it 
light by reflection from the Sim, when direct day-light 
cannot be had. Suppofe alfo, that the inhabitants of the 
fatellites of Jupiter, Saturn, and the Georgian planet, were 
to look upon the primary ones, to which they belong, as 
mere attractive centres, to keep together their orbits, to 
direct: their revolution round the Sun, and to fupply them 
with reflected light in the abfence of direct illumination. 
Ought we not to condemn their ignorance, as proceeding' 
from want of attention and proper reflection? It is very 
true that the Earth, and thofe other planets that have fa¬ 
tellites about them, perform all the offices that have been 
named, for the inhabitants of thefe little globes; but to 
us, who live upon one of thefe planets, their reafonings 
cannot but appear very defective; when we fee what a 
magnificent dwelling-place the Earth affords to number-, 
lefs intelligent beings.” 
As to the influence of the Moon on the changes of thq 
weather, and the conftitution of the human body, it may 
be obferved, that the vulgar dodtrine concerning it is very 
ancient, and has alio gained much credit among the learns 
cd. 
