New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1880-01-04
SCIENCE FOR THE PEOPLE.
THE DISTANCE OF THE SUN.

THE DISTANCE or THE sun.
Mr.. d. p. Todd, of the Nautical Almanac
| Office Washington, has an interesting lnVesu-
CATION in the January number of The Amg icGn
Journal of Science, into the distance or the
sun from the earth as deduced from the We
ocity OF light. Collecting the various deter
limitations of The velocity OF hight when are
mt all Trustworthy, Mr.. Todd finds that the
greatest velocity per second Is $40, ~
kilometres. the smallest 299,692 klIom Home aeo
kilometres, or 1S6,360 miles per see
ond Next. comparing the results OF the
investigations of Delambre and Glase-
napp. as to the time required for hight 10 ira
verse the mean radius of the earth's orDlt, II
is found that this interval is 1858 seconds
Combining this with the velocity OF hght a.
ready deduced the mean T dius OF the earths
orbit is seen to be 149, 100000 kIIometers'
or 81, S66,O00 miles; and taxing H of
ting's value of the equatorial ra aanS 7o 0
the earth at 6377.377 kilometres Of, 3962.n9O
miles this is equivalent to a solar palallaX
of $500 seconds. Allowing for rev
small probable errors, MI Iodd hha'y
concludes that the experimental deterlnlna,
tions of the velocity of light, combined
with Astronomical data, give as the sun pa
ralaX S.SOS seconds, and ITS mean distance ds
149, $40, 900 kilometres, OF w, SoO'OOo lniics'
Mr.. Downing, of the Royal Observatory,
Greenwich has also. says Nature, just made a
determination of the suns mean pafailaX llUlii
obspryat lions of Mars in dcclinatlOn ut the op-
servatories of Leyden and Melbourne, during
the very favorable opposition OF the pilnet III
1877, the same comparison star having beeh
uscd az both stations. The observations were
made i'm July and August he re-
suting mean Daralax Is 90 secOn1s'
with probable error 81 -tOOoI Secohos'
The value obtained by Professor Ne"conp
from similar observations IN ls62 was o'ooo
seconds. while that which Leverr1er, the great
French astronomer reached Is the result OF
his investigation into the planetary thtoric'
was $50 second. In Professor NGwc9mG >
Daper on the suns mean distance IN the W asu-
lngton observations for 1860, the solar palai-
lax was put at S.S4S seconds result when
has been generally adopted by astronomers,
and which makes the suns mean distance oniy
n trihe less than that just determined ny MI
Todd from the vcloc ~ of light.
THE PHENOMENA Or RADIANT MATTER
Mr.. William Crooles, the eminent EngliSh
chemist the inventor OF the sInguhlly cell
cate little instrument cdi'd the iauOmetci'
and known all the world over Tor MS lhNtsu-
oations INTO Che subtle my Sttncs OF gases
gave recently at the London Institution an
experimrutai demonstration OF laie re-
SCI riches Ou radiant matter. lie observed llai
modern research during the last sixty years u'd
greatly enlarged and modined our views on .n5
constitution OF gases. which were now believed
To be composed OF small PARTICLES OI mOiCCuies'
hat were constantly moving III every dlitc-
ton with VclUCltles Ot all conccVable HaShl-
tudeS As these molecules were exceedingly
numerous, It followed that no molecue
could move far IN any direction without
coming IN contact with some other moictulc ;
Inn II We exhausted the air OF gas
contained la "A closed vessel the number
oil molecules became diminished, ana the
| distance through which any one 0i thcm
| could move WITHOUT coming IN contact WIN
/ another was increased. the length OF the mean
free path beng nvcl>cly proportional to the
number OF molecules present. Inc iurther 'his
process was carried. the lJLger became the aver
ace distance a mOlCculc could travel before
entering into col sion; or, IN other WoldS'
the longer its mean irce pain, the more
the physical properties oil the gas OF ar were
modified.
Thus at a certain point the phenomena
of tie radIomctcr became possible ana
on pushing the rlrciActiOn still turtheI-
l. e., decreasing the number OF molecules IN %
given space aud leugthculng then mean nee
path-,he experimental results were obiaihaDle
which Nh CTookcS fully explained ~ a lecture
delivered by him to the British Association at
sheffield, IN August last. - distinct, ne re-
snaIk,d, were these phenomena from anything
which occurred III All oT gas nj the oluhaly
tension that Wc were led To assume that we
were here brought lace to face with matter IN a
fourth state OF oOudltiOn-a Condliion as l"I
removed from the state of "a, a. gas WAS from
"A maud. ln some of It's properties, ia"iaht
u,atIri was as material Il, wood or mon Whiic
IN other properties u almost assumed tie char
aCtcr # radiant energy. we hau dVludl'l
touched the border land where matter aud
fore. seem to merge into each Othti-lhc
shadowy rcah between known and unknown,
winch ior hIm had always bad peculiar temp
tutious He Vcnuurtd to think that the great
c,t scientific problems OF the future would ina
their solutions in tins bor0cr land, ana even
beyond thcTe, II seemed 10 hliI, lay intimate
realities, subdc, iaI-rcachlng and wonderful.