re starting in,
put a large cross on pages 4 and 5. For any calculations you are going
to make, these pages are unnecessary and they are liable to lead to
confusion.

Sun time of the mean sun at Greenwich is given for every minute of the
day in the year 1919 in the pages from 6 to 30. This is indicated by the
column to the left headed G.M.T. Turn to page 6 under Wednesday, Jan.
1st. You can see that the even hours are given from 0 to 24. Remember
that these are expressed in astronomical time, so that if you had Jan.
2nd--10 hours A.M., you would not look in the column under Jan. 2nd but
under the column for Jan. 1st, 22 hours, since 10 A.M. Jan. 2nd is 22
o'clock Jan. 1st, and no reading is used in this Almanac except a
reading expressed in astronomical time. Now at the bottom of the column
under Jan. 1st you see the letters H.D. That stands for "hourly
difference" and represents the amount to be added or subtracted for an
odd hour from the nearest even hour. In this instance it is .2. You note
that even hours 2, 4, 6, etc., are given. To find an odd hour during
this astronomical day, subtract .2 from the preceding even hour. For any
fraction of an hour you simply take the corresponding fraction of the
H.D. and subtract it from the preceding even hour. For instance, the
declination for Jan. 1st--12 hours would be 23 deg. 1.8' or 23 deg.--1'--48", 13
hours would be 23 deg. 1.6' or 23 deg.--1'--36", 12-1/2 hours would be 23 deg. 1.7'
or 23 deg.--1'--42", and 13-1/2 hours would be 23 deg. 1.5' or 23 deg.--1'--30".

Now to the right of the hours you note there is given the corresponding
amount of Declination and the Equation of Time. Before going further,
let us review a few facts about Declination. The declination of a
celestial body is its angular distance N or S of the celestial equator
or equinoctial. Now get clearly in your mind how we measure the angular
distance from the celestial equator of any heavenly body. It is measured
by the angle one of whose sides is an imaginary line drawn to the center
of the earth and the other of whose sides is an imaginary line passing
from the center of the earth into the celestial sphere through the
center of the heavenly body whose declination you desire. Now as you
stand on any part of the earth, you are standing at right angles to the
earth itself. Hence if this imaginary line passed through you it would
intersect the celestial sphere at your zenith, i.e., the point in the
celesti