The description and use of a joynt-rule fitted with lines for the finding the hour of the day and azimuth of the sun, to any particular latitude, or, to apply the same generally to any latitude : together with all the uses of Gunters quadrant applyed thereunto ...
Brown, John, philomath.
PROP. 17.
To finde the hours distance from the Substile in all Plains.
As the latteral tangent of the hour
from the proper Meridian,
To the parallel sine of 90:
So is the parallel sine of the Stiles ele∣vation,
To the latteral tangent of the hour
from the substile.
