[ 523 1 
its index, y. Turn the handle till the hour-index 
on its circle points to the time of new moon, and, 
holding it there, fcrew faft the collar on its axis. 
Laftly, elevate the machine till the fun fhines thro’ 
the two fight- holes on its pedeftal ; and the whole 
will be rectified. 
To reSiify for /hewing by candle-light , proceed, in 
every refped, as above, fave in the laft article ; in- 
ftead of which, place a candle before the machine, 
about four yards from it, fo as the fhadow of the in- 
terfedion of the threads, in the middle of the frame, 
may fall precifely on that part of the globe, to which 
the crooked wire points : Then, with a pair of com- 
paffes, take the diftance betwixt the penumbra’s cen- 
tre and interfedion of the threads, and equal to that 
diftance fet the candle higher or lower, as the pe- 
numbra’s centre is above or below the faid inter- 
fedion. Laftly, Hold a convex lens betwixt the pe- 
numbra and candle, fo as the candle may be in its 
focus. 
Thefe things done, which may be as foon as ex- 
preffed, turn the handle backward until the penumbra 
almoft touches the right fide of the frame ; then turn 
it gradually forward, and obferve the following phe- 
nomena : 
i. Where the eaftern edge of the fhadow of the 
brafs penumbra firft touches the globe at the folar ho- 
rizon, thofe, who inhabit the correfponding part of 
the earth, fee the eclipfe begin on the uppermoft edge 
of the fun juft at the time of its riling. 2. In that 
place where the centre of the penumbra firft touches 
the globe, the inhabitants have the fun riling upon 
them centrally eclipfed. 3. When the whole pen- 
U u u 2 umbra 
