STANDARD - Survey Instrument Antique Center!

87
19. Remarks. When the watch is corrected by either method, it will give
-ne value of t in time directly as follows : Note the time of an observation. Apply
to this time the equation of time with Us sign, as given in the Solar Ephemeris Table
of the Nautical Almanac. The result will give the apparent time of the observation
from apparent noon, -f- when the sun is west of the meridian, and when it is east
This found is the required value of t.
2O- Reducing Observations.
Conditions. Let the notation be as before.
Let t = the sun's apparent hour angle at the time of the observation, that is the
local apparent time from apparent noon This is -f- when W. and when E. of the
meridian, or -f for P.M., and for A.M. times.
Let the value of ( be found by 18 or 19, and reduced to arc at the rate of one
degree of arc to each four minutes of time, the work being carried out to seconds
of arc.
o. Directions. For finding A when 6. , and z are given. Find A from the
following equations.
.^... ~ sin t
Check- c^ = ^In-A
c. Example.