ORRERY. 
motions, one derived from the diurnal arbor, the value of 
which is * 5 * ofa day, and the other 2=— ae in Jupiter’s whole 
motion from Jupiter’s flow motion in t 
difference of thefe two is the abfolute motion of ne pinion 
before us to be afcertained: but before we eee | this 
difference, let us fee what the period would be of the pied 
that carries the four drivers of the fatellites, without c 
fidering the deduction in queftion ; for in all probability this 
deduction was not in the a of the contriver when t 
numbers were calculated : = sof a day is juft 14 hours, for 
the period of the pinion of 21, on a fuppofition of its being 
in a ftationary fituation, and the wheels that tranfmit the 
48 —sr2 12 
motion along Jupiter’ s atm are in effeét + ag and — 
of 14 hours is 24, or an exa€t day: on the arbor of the laft 
wheel of 48 are placed four drivers to a€tuate each its fellow 
in its own period: the pairs are thofe with the values placed 
oppofite them; viz 
84 D. H. M. 
1. Satellite —. of 24° - . 1 18 0 
— 85 ‘ 
2. Ditto — of 24 - - 3 18 0 
3. Ditto = of 24 - - 7 40 
he Ditto we of 24 - - 16 160 
all the numbers, that we have here examined, have 
in time, without a remainder, and a as 
u h 
coe the Le e, has negleGted the confideration of 
econds in his calcu ations of the periods. But 
e prop 
ance is made for the drawback occafioned by the motion of 
— 
25.414285 
&c. is the number of revolutions in a forward dire&tion, 
made by the pinion 24, in Jupiter’s period of 4330.6 days, 
as before determined; then one of thefe revolutions being 
seins in - hours, as we have feen, we fhall have 
25.714285 xX 14 = 359.99999, &c. or 360 hours for the 
deduction in the’. aggregate | peguceé to hours: therefore, as 
4330-96 : 360" :: 14" : 2.™90673; that is, if Jupiter’s 
period produce a aes of 360 hours, one rotation of 
¥4 hours will have a drawback cf 2.90673 minutes, be 
taken from 14 hours, leaves 13.951555 hours as the c 
reGted period of the pinion of 21 to revolve in, inftead m 
14 hours, which would have been the period if Jupiter had 
not had a revolution in his orbit. We have now, therefore, 
the fubjoined periods from the fame a which are 
Jupiter's arm, which is thus calculated: ae 
really fraGtions, not of 24 neue but of 4 — 5 of 1359515555 
which comes out 23."916951, or 23" se™ 1%, Hence we 
ave, ; 
ee D. H. M. § 
1, Satellite 8 of 232916951 - 1 17 51 16 
; 85 : 
2. Ditto i of ditto - 3 12 42 21 
3+ Ditto se of ditto - 7 32419 
4. Ditto ~~ of ditto - 16 14 36 57 
Thefe periods are not fo accurate as thofe which we gave 
before, nor is either of the fets fo accurate as might h 
b din a machine of the value o 
by an inftrument-maker, who was 
as the cafe with J Aaa 8 
940; and a fimilar ewes oo the drawback i 
made here for the time of revolution of the pion i as 
was there for the pinion of 21. The period . 
would have been the period of the re- 
sone of pinion 23, dae the arm of Mars had not been 
carried in its revolution round the wheel 432, in his period. 
But we mutt afcertain the one neriod by calculation, as 
432 = 18.78260 are the 
of a day 
3 12 hours, which 
we did the 21 of Jupiter, thus: 
revolutions to be one of on 12 hours, or, which is 
the fame thing, 9.3913 days’ motion in the time of the 
period of Mars, which we have taken at 686, os days. 
Hence, as 686.%93 : 9.4 2"; o.P1g4o53 and the 
third term, diminifhed by the fecond, leaves T1 83595 days 
as the a period for the time of a revolution of pinion 23; 
then, 7 of this time is 24> 39" 208 for the revolution of 
Mars, which, without the correGtion, would have been 25 
hours exatily, ene another proof of the author’s in- 
ention. 
_ For wan 
t they 
had, ioags we could not take down the’ conte - the 
time. 
We return now to the earth’s motion, as we propofed. 
We have already faid, that the large wheel, a — 
ina ba 
contemporary with it,) and to give it to a wheel o 
earth’s axis, or rather to a wheel on a tube that afcends im the 
oan axis, and that communicates this motion to the axis 
by the medium of three equal pinions. It was difficult to 
obtain the number of teeth of the tubed wheel, which at 
firft we fufpe&ted was 96 alfo; in which cafe, there would 
have been an error in the diurnal train of ae 3 » or 327 days 
in 
