Omaha daily bee., 1916-01-05
BY GARRETT T.. SERvIss.

kindly tell US all ehout Sun-dial,
how It Is built, the principle underly
ing the idea. Can "a set sun-dlal give the
correct time summer and winter alikcr-
w N. N. Richmond Hill"
Horas non nurnero nisi serenss CT
count only the sunny hours'D such was
the favorite motto inscribed on the old
sun-dials, and Il reveals at once the true
application of the instrument as a meas
urer OF time, and the poetic beauty Of
the conception on which Il Is based.
The sun-dial has given to literature
one of its finest allegorical phrases, The
shadow on the dial" What metaphor or
rhetorical figure. excels that in contem-
plative power2
The slow on-creeping OF the dark gray,
delicate edged shade OF the gnomon,
gradually reaching and covering the sue
cessive figures of the hours Is a curl
ously fascinating sight, II is like the
march OF DOOM with a magnifying glass
you can see the movement OF tines
shadowy finger To the Imagination II
is an uncanny sight II is mere motion
made visible, for what seems to move
is nothing. because shadow has no
substance. There is no invention that
man has ever made which puts under
his eyes So startling an image OF the
fleetingness of life as is furnished by the
sun-dial. The movement of clock-hands
has no such effect, for that is mani
testify a purely mechanical phenomenon.
Here, perhaps lies the occult reason why
| these Instruments have never been popu-
| lar, why they were often attached to
! churches and cemeteries. why moral
maxims appeared in the notices that
/ they bore. and why, in these days. when
! ever you find a man who has taken
| pains to furnish his garden with sun
dial. you are sure to discover that he
/ Is of a meditative or contemplative dis
position.
/ The sun-dial tells the true sun-time,
at the place or on the meridian. where
1t is situated. Clocks are prevaricators
and compromisers. IL you want to know
the moment when it is truly noon you
must go to the sun-dial for that infor-
nation. Your clock will. ordinarily. give
you what is actually somebody else's
noon. situated a considerable distance
east or west OF you. while somebody
else's clock will give him your noon. and
neither will have the real noon. This is
all right for general. practical purposes
in this all-grasping age, when we have
made the world our oyster. and are con-
oerned with all sides OF II at once, but
1t In not right for certain, Numerous
persons who. for one reason or another.
want to known the exact time shown
: by the real sun at the point on the earth
where they happen to live, and not the
conventional time shown by what astron-
omers call the Fictitious sum-" which
they have created to make easy work for
clocks-nobody being able to make a
clock that could accurately follow the
sun. whose apparent motion through
the sky varies in accord with the varia-
tons OF the earth's real motion around
4 1t. -Four times in a year, about April is,
June Il, September 1 and December "A.
the clock and the sun agree.
There you have the whole philosophy OF
the sun-dial; Il holds up its motionless
finger (the gnomon), exactly In the mert-
dian on sunny days, and the sun, travel
| ing from east to west through the sky.
throws the shadow of the gnomon onto
graduated dial and causes that shadow
to move eastward across the dial. keep
ing perfect step with its own progress In
the opposite direction II shows the true
local sun-time at all seasons.
The simplest of all forms OF sun-dial.
and the easiest to make is a fiat plane
of metal OF stone, placed horizontally,
and having the limo OF the true meridian
OF the place. OF the true north and south
line. drawn through its center. Another
line, at right angles to this. is the 6
O'Clock, or east and west line.
Upon the meridian line Ia set up the
gnomon. a thin triangular piece OF metal
one OF whose angles Is q right angle.
while one OF it's two other angles is
equal to the latitude OF the place where
the instrument Is fixed upright on the
dial In such a way that it's right-angled
corner IL 81 the northern end OF the
base. or side on which II stands. while
the side opposite 10 the right angle points
directly toward the pole OF the heavens.
whose elevation above the horizon always
equals the latitude OF the place where the
observer stands.
The shadow OF the gnomon viii move
across the plate on the side opposite 10
that on which the sun shines. and will
reach, In succession, a series OF hour
lines. which must be drawn at such dis
tAnces apart as to correspond with the
relative positions Of the principal meri-
dams OF the globe.
The edge OF the shadow approaches
the gnomon before noon and recedes from
, lit after noon. Al noon the sun will shine
. directly down upon the top OF the upright
, triangle, or exactly in its plane, and
, there will be no shadow, the moon line
! on the dial corresponding. as we have al
, ready seen. with the direction OF the
/ gnomon itself Standing on the south
side Of the dial. the forenoon hours will
be on the left. and the afternoon hours
on the hight.
The proper positions for the hour lines
. on the dial can be ascertsined by a sim
4 Pile Reometrical method. which is toe
: long 20 be described here. but which viii
found. for Instance. In the Encyclopedia
p Americana. II IL very important 20 have
Z the meridian on the dial placed In exacI
accordance with the real meridian. and
the asoertAinment OF the latter is a prob
? lem in elementary practical astronomy
D Many complicated and extremely beauti'
/ ful forms Of sun-diRl were made in the
I days before clocks and watches becam'
y common. They are precious curios FOR
those who can appreciate them.