ORRERY. 
flack of annual wheels. ‘The redu@tion of the ecliptic tothe at the rate of four minutesto a degree. "Thefe contrivances 
equator, like the equation of the fun’s (or. earth’s) centre, afford the belt poffible i of explaining how the equa- 
marked within the large ecliptic circle, is given in degrees ; tion table is conftrutted of two different {ets of calculations, 
and as thefe two caufes of apparent, inequality of the fun’s founded on diftin& elements, and then combined into one 
motion are given feparately, their fum or difference (as quantity that comes to zero four times in the year, and that 
the figns are the fame or different) conftitute the whole equa- varies every day m a way that is not otherwife explicable, but 
tion of time in degrees, which muft be converted into time, that is thus rendered manifet to an ordinary arithmetician. 
Taste of Periods and Errors of the Wheelwork. 
Period. Errors in Time. ag ae me 
SOL. Y. D. He. M. SS H. M. S. F “eos 
Mercury - - —_— 87 23 14 37 +o o 148 o 60 618 
Venus - - — 224. 16 41 53 +O 0 23 o 1 32 
7. = = 2 6a 72 2 3 0 0 25 
- - = — 7 fe) 4 + 1 4 I 2 Ig 9° 
Vetta - - - — I ) 2 
ean ; _ cn 13 - 5 not perfectly deter- 
Pallas and Ceres - — 1680 2 44 27 = 
Jupiter - — 4330 197 30 #| + 2 51 31 © 35 36 
Saturn - - — 10746 21 18 25 + 1 58 25 Oo Io Oo 
Georgian - . — 30589 8 32 25 +o § 26 oS) 
M - - — 29 12 44 1.2 —o o 1.6 © oO 52 
Ditto awh —_ 27 13 +18 32 —o oO 1g Oo rT 2 
Ditto node 18 223 14 49 © — 4 §2 24 o 39 +9 
Dimenfions of the Wheels and Pinions. 
Planets. Wheels, — in| Teeth per Inch. Planets. Wheels. — | Teeth per Inch. 
78 2.0 12 Farth’s paral- ; 62 2.16 9-16 
1 Mercu 97 2.5 12 lelifm 62 2.16 9-16 
y 108 304.2 10 : : f 50 1.50 9-4 
34. . 08 ‘se Diurnal motion a ae 3.00 Oud. 
118 2.0 12 Ditto on the an- 5 go 3.0 9-5 
. 63 265 12 nual bar ) 45 1.5 9-5 
ents 58 3°42 10 Wieckiv motion. 2 80 2.17 11.7 
64 1.08 fe) y q 70 1.90 11.7 
Farth - | 85 2.25 12 To Jupiter’s § 70 2.51 8.75 
85 2.25 12 moons ) 55 1.99 8.75 
. 42 1.56 8.5 | 107 2.25 15 
ai - 4 79 2.94 8.5 15 0.31 15 
Velta - - 4 29 0.97 9-5 Lunation - §¢ 12 0.25 15 
106 3-53 9-5 86 1.81 15 
: 31 0.84 11.8 3 62 1.31 15 
june - | 135 3.66 11.8 ( 62 2.16 get 
: 30 0.8 11.8 24. 0.84 g-1 
Ceres and Pallas { 138 3.7 118 Nodes - 7) 31 0.87 11.3 
. 14 0.35 12. 9 2.13 11.3 
Jupiter - 4 166 415 12.6, 64 1.14 17.8 
53 2.32 7.25 oe revo~ _67 1.20 17.8 
] Saturn - 59 — ue - O-74 a 
4 24 II. 4 0.82 
121 3.26 11.8 60 optional. 
86 . 2.93 9-3 SUPT EEG AED 2 { 60 ditto. P 
46 I. . ° I. I 
Georgian 28 ae : 4 : 1. Satellite - 4 a a 16 
| 2 | ae | ge [ape - dq] 2 | cB | ag 
120 2 i2 6 1.02 14.3 
4 The annual rhe 23 ee 12 3- Ditto - 4 60 1.33 14-3 
of the Earth 61 1.65 12 20 0.58 11 
: 0.28 4. Ditto - | 
385 12 61 1.77 I 
241 6.6 12 
