AsTR ON o M Y.

• a

thence it is seen continually acceleratesMotion towards the P erihelium, hrmanner as the Laws of Attraction r e( lThe Comet is represented by a smaH (

Ball, carried by a Radius Veclor, or e

jn an elliptic Groove, about the Sun .J

of its Foci ; and the Years of its * ^are shewn by an Index moving

J nd 5^

the least Distance of the Centres of the Moon adow exceeds.the Sum of their Semidiameters, 1 ebe no Eclipse of the Moon, as at D. But wh .jNiuD istance is less, the Moon must be partly or wW aS ryolved in the Shadow, and so suffer an Ecl'PjSjB an.d 23 ; in which latter Cafe the Moon P athe Diameter of the Shadow. $

29. But in a certain Position of the Shadow 3 , g $$least Distance pf thp Centres N C is equal to £of the Semidiameters ; and therefore 23 C is

Limit for Lunar Eclipses : To find which, we x) 1— 63' 12" nearly when greatest, and the Angl e

h

8-9*°?/

— 5 0 00'. Therefore firyAs the Sine of the Angle N js C=- oo't^

Is to Radius 90° oc/^

So is the Logarithm of the Side NC = 63,2 ^

To the Logarithm of the Side 23 C—723^,2 22Hence if the Moon be at a less Distance fr° 111 ^, 0 tb^

'^rOC° :

ii U4C ivivuu u<- UL a. j.yiustiiv,v * * . * >t

8 than 725'= 12° 59 there will be an Ecl'P lc> #wife none can happen. , S^°ii

30. If the Earth had no Atmosphere, ^ . e J P’would be absolutely dark, and the Moon ‘ ia ?? e{ cquite invisible ; but by means of the Atmofp £of the Solar Rays are refracted into and mi^e jij t

Shadow, by which the Moon is render’d vrmidst pf it, and of a dusky red Colour.

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