New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1880-08-08
SCIENCE FOR THE PEOPLE.
HISTORY OF THE LUNAR THEORY.

In on interesting paper on "Recent Ke-
searches on the Lunar Theory by John n.
Stockw in The american Journal OF Science,
the writer gives aD historical ,skf tch OF tho
efforts OF astronomers to reconcile theory with
observation. Beginning v it'll TychO Brahe, IN
modern times, the elements and theory OF the
moons motion were so imperfect that the
observed disturbances forced him to recognize
the existence of two considerable inequalities
which ere at the time unknown to the science
of Europe. The discovery of these inequalities,
" hich have received the names OF VARIATION
and annual equation. VAS the last gTea step
tow ard the perfection OF the lunar theory, which
pre- ceded the discovery OF the physical cause OF
the inequalities. Since that memorable epoch
the researches of mathematciaDs nave ln-
structed observers in regard to the magnitude
and laws of numerous inequalities which must
necessarily affect the moons motion. Inc
labOrs of New ton and HALEY reduced the
trrOis of the theory to about the eighth part OF
a degree while Mayer, by the aid Of theory
and more accurate observations, succeeded In
reducing the errors TO less than the thlrlleth
part of degree. Later still, the researches
of Mas and Burg, according TO the authority
OF La Place, reduced the errors OF the theory to
less than one quarter or minute OF are! IL
this last degree OF precision was al any time
really attained, it must have been owing to
the partial compensation of errors of theory by
the errors of the elements because the theory
very soon began To depart more ana more
widely from the observations and astronomers
have been obliged to suspect that the moons
motion was affected b. one or more cqultlOES
of very long period, which theory is hopeleSsly
unable 10 point ont.
About the middle Of the present century, new
tables Ot the moons motion were constructed
by Hansen f; and, considering the broad basis
of ObSel vallon and the eiabCIately developed
theory Of her motion, the hope was Jus!ihed
that the elements and theory were 50 perfectly
known, that they would permanently represent
the observations. But this hope seems 10 have
been i'll founded. In very few years the OBJ
scrvatiOns Enthusiastically Indicated a growing
discodaNcc, which has continued tlH the
present time; and Notwithstanding the labo-
rious investigations which have been made in
order to detect the laws and the cause no sltlS-
factory explanation has yet been attained. II;
saws Mi. StnCkwcl. we consider the nature ana
magnitude of the dIsc0Tdances which now per
tain 20 the best tables of the moons motion,
We can hardly avoid the conclusion that thty
are not due 20 the terms III higher order OF
magnitude which have been ne-lect+d IL the
development 0f the theory. lhey must
therefore, result from some systematic error
among terms OF more Importance IA the inlliI
theory.
THE GREAT SOUTHERN COMET.
An interesting paper has been published BY
Professor Kiinkcriues, OF GOttingen, oh the
| great comet discovered by Dr. Could, at Cor
doba, last February, and It's supposed previous
| appeaiances Its object Is To point out That
| the probable identity oil this comet with those
i
| because it does not appear to have leeh SEEM
! although so conspicuous an ohrct, hclWctn
! those years. 80 nearly docs 1t approach the
! sun (Withiu. indeed. about 100000 miles OF
| its suIiace) that the resistance 10 It's motion
when at pcTiheliOn is likely to be sufficient To
! produce very considerable dmlnutlOn III its
| periodic time, the case being, IN fact, one OF
! resistance from the suns atmosphere itself,
and not merely as has been c0pjectuTed III
| the case Of Enckc's comet, from IN ethereal
medium presumed to exist within the orbits
Of at least some of the planets. Hence there
Is nothing cXilaVagant in the suppOSllOn
that the resistance OF the part of the corona
within which the comet passes (many OF tAc
proninences which, under the old name OF red
flames, played 50 important Part III the us
tory of solar cclIp-CS, extend to more tAah
double the distance from 9hc suh ) surface
| within which the comet comes AT ptilheHohl
NAV be quite sufficient to diminish lis period
| of revolution from 10 years 10 81 years
! Carving this view still further back, ITO
! fessOr EhnkeTtues contends that 1t y probable
! the same comet may be Identical with one
seen and dcscribedby Aristotle III the year - e..
! 37l when the philosopher Was OILY thirteen
yraIs Old and silll living IN lis birthplace,
| StaeIfa He considers il likely that whilst TIE
/ pfrioI of revolution from Is {. 81 to !; -.
| / GGS was lob years, it was diminished by
! the resistance OF the suns atmosphere HiSt 10
! 10 and then 10 81 years; aud iHthci, thtI
/ n has al the late passage through peiihcll"h
! been decreased to i years, 20 that, II tins
/ view be correct, another return OF me comet
| MAY be expected in the autumn OF 1871