3

8 We Dſe ofebe Altimetriok Sralę. 161i 11, and ſo forward till your account fall upon F: which muſt be 4

a clock paſt(12 or) Midnight.

Example II. Upon the 8 of Aaguſt, the Star Aquila was ſeen on theWeſt ſide of the Metidian, and the hour of it was found 3 and æ an hourand 4 a quarter. The Thred therefore being laid upon that Star wouldbe as the line A G, and the Bead(rectified tothe 4 hour and 4 quarter)Would ſland at the point G. So that the next Hour- line on the left handof G, muſt be called 3 a clock, and the line F muſt be 8 a clock. Then,

the Thred being remoyed to the day of your Month( Anguſt g, in che

upper cireular Iine of Months) will lie in the line AB; and the Beadat B will ſhew. the Hour of che Night(if you keep your former account)

to be 4 and half paſt I a clock. For if E be 8 a clock(as is before expreſ-

ſed) chen the laſt hour of the limb is 17, the firſt is 12, the ſecond 1beyond which the Bead B is about 22. of an hour. Therefore chehour of che Night is t a clock 2 2 min. i N

15 thele Examples tlie manner of che work will ſuffteiently appear inall ea fes...* 1

Tbe Uſe of the Altimelrick Scale.HE Scale on the Fore-ſide of the Quadrant next to the equalLimb is here called the Altimetrick Scale. It is numbred by r,25 3, Ce. to 10, 20, 30, Cc. to 100. Fach of which numbers arebeſt ſuppoſed to be 100 fold, vr. 100, 200, Cc. to 1000, 2000,& e.to 10000; and all the lefſer parts eſtimated accordingly. The

ground on which you ſtand to make your menſuratiom, is alſo ſuppoſed

to be a juſt Level.5 1. 8 2

I. T5 find am Height at one Olſervatlon.

Et your Station be at E; and the ſights D A directed to the point1. E; che Thred A B cuts off the parts CB in the meaſuring Scale:which parts muſt be remembred.— Then meaſure from your Station E,to the point H, vhich is juſt under F. And always in this caſe multi-ply chis diſtance EH by tſie fore. named parts of C B, and from the Pro-dust cut off three figures toward the right hend. The Remainder is che

Altitude G F. To which you muſt add H G, or D E, the height fromvyour eye at D to your foot at E. ö f

. Thus