ORRERY. 
a rotation produced by the mechanifm, if the wheels oe 
it, independently of the proper motion depending 
aaa calculation, which pra gr motion or acceleration 
ele imated ; 94 revolves once in 
5 
A. 
ee 
ar by m ofition on the annual bar 
alist that of 60, w is contemporary by being oheed on 
the fame common arbor; but the pinion of 12 is actuated 
. 60 : 7 ; 
by this laft wheel aa or five times round in a year, as is 
alfo its contemporary wheel of 36, which again drives the 
laft wheel of 60; hence 5 x 36 = 180 teeth of the laf 
wheel are brought into action by thefe means in every year; 
but the laft wheel has got only 60 teeth, therefore = = 4 
are fo many entire rotations per annum produced by a man- 
ner in which the mechanifm is placed, befides the 11.625, 
or 305225 
31-33 
train ; the whole number of rotations, therefore, are 11.625 
A Qo tA GE a Pe Ne i we 
fhall obtain 24% 2 -°6 for the whole period of the 
fun’s rotation, as Produced by the conjoint operations of the 
train and annual bar. 
rotations occafioned by the proper a€tion of the 
Int me way muit the whole periods of the in- 
ferior planets be afcertained; for the long train which 
actua he fun tation is common to both thefe until 
we arrive at the laft pair of each: the movement of Mercury, 
if we put down again all the wheels concerned in producing 
94 26 
26 
12 
the motion of this planet, will ftand thus, x ra x 
ch aes , the effe€tive portion of which i is 4 x Fy 
15, I 60 
110.293 days for the period produced in the 
regular way: the oe bape 7s nee in the fam 
way as that of the fun was, is 5 x or 75 teeth in the 
laft wheel, or wheel of 88; eae TS 8522727 
of a revolution conftitutes the acceleration in ve cafe, which 
365. s 
revolutions produced 
added to 3.3116234 (or 23 
by the regular action of ee nai amounts to 4.1638961 
ie ee da m 
revolutions per annum 3 and ——— i mC 872 14" 47™24.59 
is the whole period arifing out of the compound motion. 
Again, the other planet Venus has for a whole train 2 x 
— X 24 x — or ineffea 24 
26°24 15 I 
75 
days without the acceleration, which in this inftance is oe 
12 
_—_—? 
405-25 
or 3d of a revolution; we have then 
= 1.295212 
revolutions without the acceleration or en -333333> 
which together make 1.628545 revolutions per annum, or one 
365.025 
1.628545 
joint = of tan caufes of motio 
not quite certain ee or not the reader vou 
revolution in 
or in 224¢ 6 36" 59.572 from the 
€ opportunity to notice 
in motion, will have no difficulty, after perufing this account, 
in ea ate ba neha the feparate fources of motion, 
owever he might have been agen! La as to affign 
to each its — quantum of t 
And now that we have pas - ihe refult of our exa- 
mination, 7" appears by a comparifon of thefe periods with 
the exact times of the refpective jonas antes — 
the aftronomical tables, cok they ar s fo 
rate as might have been expected ee tach ehh ae an 
lations, and fuch complex mechanifm 
Befides thefe portions of Beet cit there are fome 
pheres, ‘when a three inch globe is put on as the earth’s re- 
prefentative, which is an Ede ean apparatus; the ufual 
globe being 13 inch ball of ivory ; the movement, to a nfwer 
12 a3 876 
"6 * 60 
of 24.97435 = 364° 152 0™ 44%, soa este hate what 
it ought to be, about 15 hours moti ; but this 
deviation is of httle confequence, as bite froin of the 
lamp is se to peep the earth, while : slg of 
day and night, e fucceffion of the s, &c. are 
under ea aeeion: he lamp bas a convex es laced, 
we prefume, at the diftance of its focal convergence from 
the light, fo that the rays which pafs through may proceed 
ata to each other to the little globe. 
_The wheels, or ue: rings of Mer 
this purpofe, i of the fun’s rotation, viz. 
ercury and Venu 
eftia purp 
wena ae it isc alc ula ta to a in a ple 
manner i of its external appeara cann 
mifs the er pah of this m 
teeth of the two laft wheels in each of Rowley’s movements ; 
225 
which for Mercury are ? for Venus —= - —2, and for the Sun 
60 25 
= =. 
the laft movers were intended to reprefent sae days; the 
periods being to each other in the neareft whole numbers, as 
225 re{petively ; and w ini 
u 
It occurred to usat the time of examination, that 
i 
