228

Appendix-

ing the Equation, we have x -

= T V, the Time required. Vi

13. But if the Order of the Qh* er ^tions be such, as that the Observati 01 ^the Shadow of the Gnomon in f i Sin the Middle between those of the Sh a ^in h and g ; then will AT = E £’ ^

so a b, and the Equation will beeoM^

ac-

•a

d

TV; which gives this

that

i b

; c —: d : : a : X,

G.H : : AT :

2 d + 2 c

logy,

2 F G + 2 F H : l>. T± : : AT' : * '' H/14. I 8HTEE illustrate this Calcula^^fan Example of each Cafe. In the ^1500, Bernard Walker , in the ^ 0 fdune, at Nuremberg , observed the Ch 0 ^ , 3the Sun’s Distance from the Zenithlarge Instrument, as follows; .

June 2, 45467T (June 8, A3

9, 44934 }> and June 13 . ^ ggi.6, 44990J (Jim. ■- ^1

The Difference of these. Chords arevery near to the- small- Distances FE H ; therefore c — 533, and ^ ^ ^

c — is 477; and since thb, Time v ^ 4Days between Observation, therefore a -p,Whence we have 1.17.8 ; 477 7 ' 0 fh