Although, as mentioned last month, the sun gives out such a vast amount
of heat and light, we must remember that these are sent out in all
directions, and that we receive comparatively a very small portion. The
best estimates make our part one twenty-three-hundred-millionths of the
whole. But this quantity is no trifling matter, and its effects are not
to be overlooked. Speaking of the general effect of the sun’s influence,
Prof. Lockyer puts it in this way: “The enormous engines which do the
heavy work of the world—the locomotives which take us so smoothly and
rapidly across a whole continent—the mail packets which bear us so safely
over the broad ocean—owe all their power to steam; and steam is produced
by heating water by coal. We all know that coal is the product of an
ancient vegetation; and vegetation is the direct effect of the sun’s
action. Hence without the sun’s action in former times, we should have
had no coal. The heavy work of the world is, therefore, indirectly done
by the sun. Now for the light work. Let us take man. To work, a man must
eat; does he eat beef? On what was the animal which supplied the beef
fed? On grass. Does he eat bread? Of what is bread made? Of the flour
of wheat and other grains. In these, and in all cases, we come back to
vegetation, which is the direct effect of the sun’s action. Here again,
then, we must confess that to the sun is due man’s power of work. In
fact, all the world’s work, with the trifling exception of tide-work,
is done by the sun; and man himself, prince or peasant, is but a little
engine, which merely directs the energy supplied by the sun.” The use of
the sun as a time-piece is perhaps more frequently thought of than any
other, since its value is constantly presenting itself. Each day, as noon
approaches, the question occurs, “How is the time?” and when possible,
the time of crossing the meridian is compared with that exhibited by the
clock. For this month, on the 1st, noon by the sun occurs at 11:57 a.
m. clock time; on the 15th, at 11:56 a. m.; on the 31st, at 11:57½ a. m.
Another method, though not very accurate, of determining time, is the
noting of the rising and setting of the sun. One difficulty here would
be the obtaining of a good horizon, such for example, as could be had at
sea. The following times answer very well for most parts of the United
States and Canada: On the 1st sun rises at 5:02 a. m. and sets at 6:52
p. m.; daybreak occurs at 4:08 a. m., and twilight ends at 8:46 p. m.;
on the 15th, sun rises at 4:48 a. m., sets at 7:05 p. m.; daybreak at
2:44 a. m., and end of twilight at 9:09 p. m.; and on the 31st, sun rises
at 4:37 a. m., and sets at 7:17 p. m.; daybreak occurs 2:24 a. m., and
twilight ends 9:30 p. m. During the month the days increase in length
some fifty minutes. On the 31st the sun reaches its highest elevation
above the horizon, which in latitude 41° 30′ north is 70° 33′, nearly.
As we are now moving away from the sun, its apparent diameter diminishes
from 31′ 48″ to 31′ 37″.