MON 
«f straw and chopped wool, rose to an ele- 
vation of about six thousand feet. This 
power of ascent BI. Montgolfier attributed 
not merely to the rarefaction of the air 
from the heat (which appears to be the 
true cause), but to a species of gas specifi- 
cally lighter than common air, supposed to 
be disengaged from the burning substances. 
When the event of these experiments was 
reported at Paris, the philosophers of tliat 
capital immediately thought of applying, for 
the purpose of inflation, a gas wliich they 
knew to be eight or ten times lighter than 
common air, namely inflammable air, and 
trials were immediately made upon that 
principle, which have proved highly success- 
ful. In the mean time Blontgolfier con- 
tinued to extend his plans, and on Septem- 
ber 19, 1783, he exhibited before the king 
and royal family at Versailles a grand ma- 
chine, near sixty feet higli, and forty three 
in diameter, which ascended with a cage, 
containing a sheep, a cock, and a duck, 
and conveyed them through the air in safety 
to the distance of above ten thousand feet. 
Emboldened by this success, M. Pilatre de 
Rozier first offered himself to undertake 
the hazardous adventure of an aerial navi- 
gation in a new machine of Montgolfier’s, 
of still larger dimensions. After first as- 
cending alone to the height of eighty-four 
feet, he again seated liimself in the car with 
the Marquis d’Arlandes, when tliey gave all 
Paris the astmiishing spectacle of hovering 
in the air over that city for about nine mi- 
nutes at tlie height of three hundred and 
thirty feet. Tin's brilliant experiment 
caused the annual prize of the Academy of 
Sciences to be awarded to M. Montgolfier, 
and from that mra, October 19, 1783, the 
atmosphere has been a new field of human 
daring. The first principle of ascent, how- 
ever, though applied in various succeeding 
instances, gradually gave way to the safer 
and more efticacious one of a gaseous fluid 
permanently lighter than the air. In one 
unfortunate instance the two modes were 
combined, and the result was, that the bal- 
loon caught fire, and occasioned the death 
of the first adventurer, Pilatre de Rozier, 
and his companion Romain. Montgolfier 
was rewarded for his discovery by admis- 
sion into the Academy of Sciences, the 
cordon of St. Michael, and a pension of 
two thousand livres. He died in 1799. 
MONTH, in chronology, the twelfth 
part of a year. 
Time being duration, marked out for 
certain uses, and measured by the motion 
MON 
of the heavenly bodies, there thence rcsulte 
divers kinds of months as well as years, dif- 
ferent from one another according to the 
particular luminary by whose revolution 
they are determined, and the particular 
purposes tliey are destined for : hence 
months ate of two kinds, astronomical and 
civil. An astronomical month is that which 
is governed either by the motion of the sun 
or moon, and is consequently of two kinds, 
solar and lunar : a solar month is that time 
in which the sun seems to run through a 
whole sign, or the twelfth part of the eclip- 
tic. Hence, if regard be had to the sun’s 
true apparent motion, the solar month will 
be unequal, since the sun is longer in pass- 
ing through the winter-signs than through 
those of the summer ; but as he constantly 
travels tlirough all the twelve signs in 363 
days, 5 hours, and 49 minutes, the quantity 
of a mean month will be had, by dividing 
that number by 12 ; on this principle, the 
quantity of a solar month will be found to 
be 30 days, 10 hours, 29 minutes, 5 seconds. 
A lunar month is that space of time which 
the moon takes up in performing its course 
through the zodiac, or that measured by 
the motion of the moon round the earth ; 
and is of three kinds, fir. periodical, syno- 
dical, and that of illumination. The lunar 
periodical month, is the space of time 
wherein the moon makes her round tlirough 
the zodiac, or wherein she returns to tlie 
same point, being 27 days, 7 hours, 43 mi- 
nutes, and 5 seconds. 
The lunar synodical month, called also 
absolutely the lunar month and lunation, is 
the space of time between two conjunc- 
tions of the moon with the sun ; or the 
time it takes from one conjunction with 
the sun to the next; or from one new moon 
to another : the quantity of a synodical 
month is 29 days, 12 hours, 44 minutes, 
3 seconds^ and 11 thirds. The quantity of 
a synodical month is not the same at all 
times, for in the summer solstice, when the 
sun seems to move slowest, the synodical 
month appeareth less, being about 29 days, 
6 hours, 42 minutes ; but in the winter, 
when the sun’s motion seems faster, the 
moon does not fetch up the sun so soon, for 
which reason the synodical month then 
seems greater, viz. 29 days, 19 hours, and 
37 minutes, according to the observation 
of the same astronomers : so that the first 
quantity given of the synodical month, is to 
be miderstood as to the mean motion. 
From what has been said, it may easily ap- 
pear that the difference between a peiia- 
