The times dispatch. [volume] (Richmond, Va.) 1903-1914, 1903-04-05
The EQUATION Of Time.

81, 4 Massanuttan,, Page county, Va M
Editor OF Tho Times Dispatch: vs.
q With your permission 7 will aid your
5queriBt In regard to- the Equation Of Time:
by adding to what has already been said
r Tho earths orbit Ia not q circle. but
an ellipse. Kopler's First Law: 1.-THE plan
cts movo In ellipses with the sun In one.
focus' 1t follows from this that they
have not uniform motion, planet at
aphelian will have an s1ncr ceased velocity
to perhellan, and retarded from perihel-s
Ian to aphelian. & Fs
until recently astronomers thought
that the time Of the rotation Of the earth
remained exactly the same from century
to century, and that there was therefore
no change in the length Of the day. But
1t Is now thought that tho ocean tides,
which move around the Garth In the
other direction, by their friction may be
gradually making tho rotation OF the
earth slower, and thus slowly frightening
the day, But as q day is at the most
only one sixty-sixth OF q second longer
than 1t was 2,5oO years ago. we con-
slider tho length OF the day practically
inYariablo." s
Tho 6idereal Day: From the time o
star orosses our meridian until 1t crosses
It again is about four minutes shorter
than the moan or solar day. 5.
l@5"Sun t!no agrees with true or moan
tlrne only on four days Of tho year.
| Keplers third Law: 1.-THE squares OF
the times OF revolution Of two planets are
proportional to the cubes Of their dis
tances from the SUM-"
1t follows from this that the planets
nearest to the sun move much faster than
those moro distant, and also that all plan
| cts move with the greatest velocity when
nearest the sun. and the least when most
distant. If such were not tho case they
would either fall into the sun. or ny out
| into space. 10 IL, RI
| NTH ,raVnlVaa around Tho in
such q manner that It requires 1868 IA ro-
| tat!ons upon Its axis to give US 805 Ia days
| In year, the effect OF one rotation being
| lost upon tho sun. Just as q person can
| destroy tho effect Of q rotation OF the
earth by, going around the earth. S
Computed by the stars we have 800 IA
Interchangeable days In O year. This period
Of timo Is divided into 1856 IA equal PEE
RODS, and clocks arc constructed to mark
1t, This timepiece the earth carries In
Its yearly journey around the sun. a
person going west around the earth In
/ a. specially constructed timepiece in
order to have local time during his jour-
ney. Els year would consist Of 1854 IA
equal periods Of "a hours. 10 avoid be-
Ing fast or slow no should speed his jour
ney so as to comply with the conditions
i by his watch are longer than the ones
| ne use, no would not DO allowed to re-
main at rest and IL he moved too fast
4 his watch would got ahead OF local time.
T. and II he moved too slow It would be
behind local time. AS the SUMS yearly
motion around the heavens among the
!, stars Is caused by the earth's orbital mo,
ton around the sun. our clock isi subject
i ia the sama conditions that affect the
4 travellers watch. 1t should be at the
i right point at the right time,
This we have learned our earth, oWlne
to her accelerated and retarded motion I
unable to accomplish, as she runs SIG 2 :,
little behind the remainder, she is enabled
to have the clock at the. right point Or
four days In the year and approxlm atelS
near, tho remaining days,
This Irregular motion Is the prln c 81
reason why mean time and clock TINS
fail to agree, ,,,o,,p