ORRERY. 
of its being nearer the interior end of the horizontal diurnal 
arbor, which is therefore not fo much lowered as the exterior 
end, while the interior pivot remains in the hole of its cock : 
it will be neceflary, notwithftanding, to pin the ratchet to 
wheel y, for the time that this wheel is made to act in both 
direCtions, which may be readily done when a hole is drilled 
through beth the ratchet and wheel y at the fame diftance 
from their centres of motion, and by the fame drill. The 
tube of the annual wheel G turns immediately upon that of 
an 0 pinions, denoted by the letters g, 4, and #3 
wheel ¢ drives the tubed wheel H in the pe f Mars ; 
5 driv s the wh ith its tube in the period of Jupiter ; 
aturn, he bridg 
wheel G, has a tube fixed to it, as feen in fg. 2. along with 
. The ufe of this tube will be feen 
ft the 
motion of 48 hours 
The large contrate 
wheel 9, with its teeth pointing upwards, is faft to the top 
of the tube of wheel abcve the frame, that revolves 
round the tube of wheel L in the fmall frames this wheel o 
< 
g pinion has a compound 
from t 
borne by the plate, Y Y, of the {mall frame, and receives its 
motion from a pin 3, at the remote end of a bar 3 7, whic 
bar is inferted on the tube of Georgian’s wheel L, and 
revolves in his period ; hence the arm itfelf revolves round 
the excentric piece, W, as its centre of motion, and therefore 
the planet carried by it has its diftance and velocity con- 
of the centre will be only one-half its due quantity ; on the 
contrary, if the excentric point be placed at double the 
riod of 10 
of this combination of wheels and 
° 
a 
ow 
ae 
EY 
et 
is) 
2. 
= 
= 
> 
ww 
Lod 
3 
Ld 
7 
a 
ae) 
Qe 
o™, 
a 
pinions, the 
1 
variations that derange thofe mean motions, and that depend 
on the place of Georgian’s anomaly at any time. ike 
manner, Saturn and Jupiter have their fyftems o 
actuated by the double contrate wheel nn, carried by the 
tube of wheel N before defcribed: the teeth that point 
downwards drive Saturn’s moons, and thofe that point 
upwards Jupiter’s. The excentric piece, round which Sa- 
turn’s arm revolves, is marked Z on the fixed tube of the 
h : 
plate AA of the fr 
their correfponding tubed wheels 2 4 and 5, in t 
periods of the 2d, 3d, qth, and sth fatellites; from the 
period 
