The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1875-01-30

tary distances and sizes. The variation OF the
method q using two stations wnefeoy sne appa'
ing OF The Observers POSITION ON account only OF
The dinrnal rotation oil the earth was employed. as
well The original method, III 1862. ana the result
confirmed the impression which other investlga-
lions mad created that the distance OF the earth
from the sun was certainly less than s2'ooo'ooo
miles.
Ll-By the velocity OF light.
Alter the dimensions OF the eartns ORBIT were
known. the velocity OF light through space was
measured In two ways by Astronomers; by the
difference In time OF the calculated ana observed
disapp and Temperatures oil Jupiter's
satellites al his opposition aud conjunction, anu
by the alteration OF the fixed stars. But neither
oil these reveals the real velocity OF light. III
renamed for FiZeau and Foucault to solve proc
lem apparently so lntractable, where velocity OF
ls5. 900 miles per second was involved This Is
not the place 10 Reproduce the method devised by
these eXpertmenters, but the result bv Foucauits
method. wnch in some respects Is superior 10
plane larry space as well as IN air. OF $50 900 miles
per second. From this we deduce the value
81. 100000 miles as the distance OF the earth iro
the sun.
IiI.-By certain irregularity in the moons ms
motion. due TO her being most disturbed oy the
sun when between the earth and sun
The law OF gravitution declares that the attrac-
ton between masses depends upon the distance
between them. The moon Is attracted 10 inc
earth by a force depending upon their distance
which is knowr. When the moon IS between the
earth ara the sun the latter tends to draw her
away from the earth, so to speak, more strongly
than to pull the earth away from the moon wnen
the moon is IN opposition A similar tendency
exists Tor all The POSITIONS OF tue moon when
nearer the sun than the earth Is. The efects OF
these differences OF attraction are shown IN the
acceleration and retarda'i0n IN her 0roit, and In
the distortion OF tnat orbit. which Is thereby
elongated III direction at right angles to the line
through the moon, earth and sun. In the mooD's
motion the Sight variation, which depends upon
TINS cause alone, can be calculated theoretically.
II we know the exact distance OF the earth from
the sun and that OF the moon from the earth the
theoretical motions oil the moon should agree
WITH the observed motions ii they do not agre G
I ne difference Is used as the basis Tor the deter
mlnatlOn oil the real distance. The perturbationS
are OF course, very minute, but the observations
are so numerous aud SO exact that, In 1854,
the eminent mathematician and lunarlan, Hansen,
actually detected the difference and ascrlDed 1t
to he true cause. TINS led to reoiscussiOn OF
the whole subject and confirmation OF Hansen's
deduction. From these results he assigned, III
1863 distance OF 9,659, 900 miles as the dis
lance OF the earth from the sun. In this method
oil lnve stigatlon we are indebted to Laplace, who
deduced "a value OF me distance, very little differ
ent from Encke's results derived from the translts
OF Venus.
IV-By an rregularity IN the eartn's motion,
due 20 her moving around the common centre OF
gravity OF her own mass Plus that OF the moon.
In iew days the success oil the French and
American p'rtles In Japan VIII he settled. Both
are uy prepared and ready for the work; all
else depends upon the weather. That result Will
be known long before this reaches the Atlantic
states. D.