The Minneapolis journal. [volume] (Minneapolis, Minn.) 1888-1939, 1903-05-06

dial the different months are designated,
SO that when the style, or gnomon, Is
properly adjusted to the date by set screw
running under the dial. the shadow will
cover the true hour angle indicated In the
elipse. The inventor of the latest dial
is Denis B. Sheahan, the sculptor Of 424
Nicholas avenue. 4.&.zz
His dial is also sometimes combined
with the old fashioned dial, SO that there
is the advantage of showing the differ
ence between the suns time and that Of
a we'll regulated clock, as the old fash
toned dial gives only the suns time, and
the analemmatic dial shows the correct
mean, or clock time for each day in the
year when the sun shines enough to make
| a shadow, without having to refer to the
tables of the equation Of time. Speaking
of his new dial, and the history Of dials,
Mr.. Sheanan says:
| Astronomy teaches that the earth
moves in an orbit about the sun com
| pleting a revolution In year, while at
! the same time it revolves uniformly
from west to east on its axis, and, al
though it changes in place, is always
| parallel to this fixed imaginary line, or
axis.
"By the first Of these motions the sun
| appears to move around the heavens,
completing a revolution in the course of
a year, and by the second, the sun, and
all the heavenly bodies have an appar-
Tent diurnal motion about the earth from
least to west.
1.-THE motion Of the earth in its orbit
/ is not equable, and therefore it happens
1 that the apparent motion of the sun is
not quite uniform; besides the plane Of
! the motion does not coincide with the
plane Of the diurnal motion. For these
two reasons the apparent diurnal motion
Of the sun differs a little from uniformity.
5.'But in the theory Of the dial we are
! to suppose that the suns diurnal motion
| is always perfectly uniform, and that 1t
moves thru the day in circle paral-
| lei to the equator. Now as neither of
! these presumptions is strictly true the
] time Of the day that is shown by d dial
/ that is not analennnatic will in general
1 differ from that shown by an accurate
clock. The difference, however. admits
of exact estimation, and the tables OF
my dial show the exact declnation every
4 day in the year
Dia1s and their making have been q
passion with me for many years, and it is
q not 50 very long ago that conceived
j the present Improvement and I do MOI
4 believe that anything like it has ever be
4 fore been attempted.
i The making Of dials. of course, re-
/ quires certain knowledge of astronomy
i a mathematical mind with an acute per:
i ception of the truths of geometry. The
lhlStory OF dial construction is one of the
most interesting in the world dealing as
it does with the works of man in his
/ progress, his various civilizations the
story Of the orations and the calling to
mind of many of the great characters in
j each of these civilizations. The history
of the dial is also filed with interesting
i customs of many peoples showing how
i they came to divide time into hours and
seconds. 81
4 This division Of time is Of course, OF
the greatest Importance, and must have
4 early engaged the attention Of the human
/ race. We find in Second Kings, chapter
Xxx. verse 9. that by miracle the shadow
i went back 10 degrees on the sundial, as a
i sign given to Hezekiah that he should re-
1 cover when he was sick unto DEATH
The men Of the world long before us
1 had very different ways OF calcuIat ine
time. The length of the day was firsj
determined by the rising and setting 81
the sun. The Babylonians began the da,
at sunrise, and reckoned that 1t continued
until the sunrise Of the next day The
/ Athenians considered the interval between
succeeding sunsets as a day. which they
4 divided into two parts. the natural night
i extending from sunset to sunrise
The Egyptians and the Babylonians
| were the first to determine correctly the
8 position of the meridian. The Egyptian,
slshoWed their skill by placing the pyramid;