NUMBERS. 
compofing wheelwork, and any particular 
affumed, that the machine moft conveniently adm 
the period in which the firft driver revolves. 
from the lunation; and the lunati 
Likewife the fatellites of Jupiter may have 
r feven days, or any 
a day, 
the machines, where they occur, under our articles ORRERY, 
and PLANETARIUM, but an account of which would lengthen 
our prefent article too much, were it given in this place. 
Numbers for fynodic Revolutions —We mult not, how- 
ever, conclude our prefent article on planetary numbers, 
before we have made f } the fynodi luti 
of the primary planets, particularly as we fhall have occafion 
e{cribe in another place, a v i i 
tions 
conjunGtions of Venus with the fun, as {een from the Earthy 
from tke Sun; the mean daily 
and Venus had no equation of the centre, and confequent 
acceleration and retardation in the different parts of their 
orbits; if we take Mercury inftead of Venus, the fynodic 
1296000 
115,877 days; 
11184.24 
but as Mercury’s orbit has confiderable excentricity, the 
ynodic period in any given year may exceed or fall fhort of 
this number by many days, accordingly as the fun’s place 
may be near the aphelion or perihelion of the planet’s orbit, 
when the conjunction or oppofition takes place. Again, i 
we take Mercury and Venus, the fynodic period will be 
period at a mean rate would be 
1296000 
8964.77 
fe& arifing from the relative fituations in their refpective 
orbits. In the fame manner we may ufe the difference of 
= 144.566 days, but {ubjeé to an excefs or de- 
tw 
period, agreeably to the refults contained in the fubjoined 
talble, which we beg leave to infert here on account of its 
novelty as well as utility. 
A Taste of the relative mean fynodic Revolutions o/all the primary Planets, expreffed in Days and Parts of a Day. 
Planets. Georgian. Saturn, Jupiter. Eales is Juno Vetta, Mars. Earth. Venus, 
Mercury 88.290 88.694 89.792 92.825 | 93.118] 94.174 | 100.888 | 115.877 | 144.566 
Venus 226 358| 229.493] 236.993| 259-355 | 261.654] 270.169 | 333-917 | 583-923 
Earth 370.713 | 378-091 | 398.892] 466.606] 474.101 | 502.813 779.938 
Mars 702.713 | 733-836| 816.434 | 1161.394 | 1208.955 | 1415-002 
Vefta 1395-950 | 1524.347 | 1930-007 | 6480.000 | 8302.370 
Juno 678.104 | 1867.166 | 2514.552 | 2952-164 
Ceres and Pallas} 1779.242 | 1993-233 2.748.674 
up 044-960 | 7253-595 
Saturn 10568°625 | 
N.B. In this table the fynodic periods of Vefta, Juno, vettor,) thofe fame calculations will be proper for exhibiting 
Ceres, and Pallas, muft not be confidered as perfeGtly ac- the tropical revolution of that planet, as feen from the fun 
curate; their tropical periods being not yet completely 
afcertained. 
loo 
top ef the table, and at the junction of 
vertical columns, in which thofe planets ftand refpectively, 
is the number 816.434, the number of days required. In 
like manner, the number of days for Venus and the Earth is 
583.923 
n the courfe of our making calculations for the motions of 
or produce the fynodic revolutions of either of the interior 
planets, be placed upon the Earth’s annual bar, (or radius 
This circumftance we have already glanced at, when calcu- 
lating the tropical period of Venus by our indiret method 
of approximation, but we will now illuftrate the obfervations 
we have made by anexample. In a fmall orrery, at prefent 
before us, the ratio between the tropical revolution of Venus 
2016 
' 3277 
wheelwork compofed of this ratio is carried by the Earth’s 
annual arm, at leaft fuch parts of it as revolve out of t 
centre of the inftrument, Venus is carried once round, inde- 
pendently of the calculations, in every year, by a pufh given 
to the laft wheel in the train, moving in the centre round 
the fun’s ftem, as the Earth’s arm goes round it, while the 
teeth of all the wheels are connected; unity is, therefore, 
ejeGted out of the ratio before the train is compofed, thus ; 
the numerator 2016 is fubtra¢ted from the denominator 3277, 
and the remainder, 1261, is taken as the denominator of the 
reduce 
and a folar year is calculated to be » but becaufe the 
