A S T R O N O M V

Cometarium isac Mn.e, which exhibits

ft

a very curiousan Idea of theMotion

'an,

° ne . hlalf of it, and cause the Earth to project a■ v her e s *c ; ' s ^ Shadow , as is represented in the Figure,

<ad,

‘OVir,

iS the Sun, E the Earth, and HBD its

°, rC * Cr to find the Extent or Magnitude of the&ir e j Shadow, the Lines being drawn as in the Fi-1 , SB^ Mangle S B M, the outward Angle S D At|j e ~ T D B S, the two inward and opposite Angles ;pitiij: viz. D S B, is that under which the Earth’s

.ftsihjp^^t CD appears at the Sun, which is notjj S ^Ual* t ^ ere f°re DBS, the Semi-Angls of the Cone,; V s Q to D S, which is the Angle under which the

‘^J^idiameter ° ~ ‘ ~

\ n Astaticien ce

1 s

'^a

A S appears at the Earth, which inace is 16 Minutes.

ft,

°tie

ic te

N 6 IS

o e ! lce Wc can find the Height of the shadowy- “ ! for in the Right-angled 'R-'"""'-- r' R r»

Triangle

CBD

I,

S

7„ . - ‘Wt, ill LUC IVlwm-rmgiLU i Iian^iv ^ ^

16 j,B lv en the Side C D — I, and the Angle CBD* 1 the'F tSS ’ t ^ iere f ore t0 6nd the Side C B, fay,

t0 the 3

* s XJ]

angent oiRadi

ius

CBD^ oo°9 °

i6'= 7.667849oo — 10.000000.

sl ity " 1=0.

ft 3 <

■ thpT -

lA Tk ij n .g thof the Side C B = 214,8 - 2.332151f);n ” ei ght of the Earth’s Shadow being at the

^ S,. Ar 4-h. ^ O ..., — , . O Comldiompfprc

'tv °U

'i 7 S e

; at its greatest Distance it will make C B

is

%t mi ^et e rs of the Earth, which is its greatestCe erice we fee the Height of the Shadow is near

6n o es as great as the mean Distance of the Moon,

? k 6o> **

the »’° re

of?k t5l « e same Manner it may b

v hnfl ^ thfft 1 \/T-^_ i n 1 1 / . .. 1 t _

-. But the Height of the terrestrial

.Tfore 3 S s ar Riort of the Distance. of Mars , andinvolve no one of the heavenly Bodies but

qj- , 'mm; ivianiici "■ uitij, «>- strewn that the%° reS *mid-° ° nSs ^ a d° w ( an d indeed of ail SpheresIam eters bear no sensible Proportion to their°L. jTr tn t i le Sun) is of the fame Dimensions withO that

193

PI. EX.Fig. 2.