The sun., 1893-02-12

| teacher OF hepler The son OF poor officer j
the army Of the Duke Of WnrtemberR. he wa
at first . tavern pot boy. but was uitimatel
sent to q charity school and thence to tn
University OF Tnbingen. He studied mathe
| matics and accepted m astrc nomical lecture
ship at Graz. In 1907. at the age OF ~. HI
published his first fanciful hypothesis. b,
| which he endcavored to discover ssms con
nectiou between the number Of the planets
their times Of revolution. and their distanc CO.
from the sun. Two years later he was invited
by Tycho Brah6to Prague. whittier the Danish
astronomer had retired from his native coun.
try. After incredible labor. through innumer-
able wrong gussses. and six years OF almo ost
incessant calculation. Kepler at length
emerged with his two first "Laws"-
discoveries which swept away all cpl
cycles. deferents. equants aud other rem.
nants o. the Greek system. and ushered
In the dawn OF modern astronomy. These
laws. 1t is we'll known. were. first, that the
planets move In ellIpses with the sun In one
focus. and. second. that the radius vector Tor
line joining the sun and planet) sweeps out
equal areas in equal times Ultimately. Kep-
Ter discovered tho connection between tho
times and distances OF the planets, for which
he had been cropping through all OF his m ature
life. This law. which he announced In 1d1S
Is that tho square Of tho time OF revolution
Tor year, OF each planet is proportionate to the
cube OF It's mean distance from the sun. His
three laws. taken together. place him In the
very highest rank OF scientific men. They in
troduced order and simplicity into what else
would have been chaos OF the details Of OBJ
servation. and they served as n secure basis
for the splendid fabric to he reared on them
By Newton.
To realize what Kepler did for astronomy It
Is necessary for us to consider some science
still in it's infancy. Astronomy is now so
thoroughly explored that II is difficult to put
ones self into the attitude OF the men OF the
sixteenth century, Let US take. then. some
other science. still barely developed. like me-
teorology. for example. The science Of the
weather-the succession OF winds and rain
sunshine and frost, clouds and foRs-is now
very much in tho condition OF astronomy be-
fore Kepler. Observation Is heaped on OBJ
servation. tables are compiled. volumes are
filled with data. tho hours OF sunshine are re-
corded the fall OF rain. the moisture In tho air.
the kind OF clouds, tho temperatures; millions
OF facts: but whore is the Kepler to study and
brood over them2 Where Is the man to spend
his life in evolving the beginnings of law and
order from the midst OF all this chaos? A life
Of such labor. crowned by three brilliant dis
coveries. was that Of Kepler. The exreri-
mental observer Is indispensable. but how
backward would science be were observations
not interpreted by thinkers like Copsrnicus.
kepler. Newton. and Laplace.
III.
A contemporary OF Kepler was Galileo. The
after was born In tho year 1864. in which Mi
,hael Angelo died. and he died In 1912. the
rear In which Newton was born. The perse-
sutton OF Calico did not begin until 1915. nor
sotn ~
famed date it lasted till his death. Born at
ity OF that city. He was an experim entail OBJ
erver. ltwas by experiment that he refuted
he assertion OF Aristotle that bodies fall at |
atee depending on their weights Galileo. on |
lie contrary. contended that the weight did |
ot matter in tho ieast. but that everything |
you'd fall at the same rate. oven n feather but |
or the resistance OF the air. and would reach
he ground at tho same time. TO convince his
pponents. he assembled ono morning the IA
nous leaning tower Of Pisa. taking with him n
90. pound shot and o one pound shot. In the
resenco Of the assembled university.
70 balanced them on the edge OF tho tower
nd let them drop together. Together they
ell and together they struck the ground. This
ictory over tho Aristotelians made Galileo un-
opular in Pisa. and he presently found his
he Offer Of a professorship at Padua from the
enate Of Venice he accepted 1t. and began
career. 1t was at Venice that Cali
20 invented the telescope. He had heard. to
Q sure. OF q toy constructed by a Dutch op-
clan out Of q couple OF spectacle lenses.
trough which, II one looked, tho weather
ocE OF a neighboring church spirs was seen
carer and upside down. Galileos instru-
lent was made on another plan from that OF
le Dutch optician. He took an old and small
rgan pipe. jammed suitably chosen
pectacle glass into either end. one
onveI. tho other concave. and thus pro-
ucsd the half OF a wretched opera glass.
,pable Of magniiying three times. 1t
as better. however. than the Dutchman's
". because it did not invert. Even with
ND rude telescope it was possible to make
hips visible from one OF the highest towers in
enice two hours before they were seen en-
ring the harbor Subsequently Calico sue
seded In making telescope magnifyine
,irty times. Equipped with this he was ready
! begin a survey OF the heavens. The first
bject he examined was the moon, where lie
'und everything at first sight very like the
and valleys. orators and
|ains. To the disgust Of tho Artist otelians, he
OF only made the moon like the earth. but he
ado tho earth shine like the moon. explain
,g by earth shine the visibility OF 1.-The old
loon In the new moons arms" Ono of the
,ock arguments against the Copernican
leory OF the earth being planet was that
10 earth was dull and dark. and did not
iine. Calico argued that it shons lust as
uch as tho moon does. and in fact. rather
ore. especially II 1t be covered with clouds.
sen from the moon. the earth would look OK.
,tly as the moon. does to us. only q little
lighter aud sixteen times as big. 1t is note
orthy that Calico made very good estimate
the height OF lunar mountains. OF which
any are five miles high and some as much as
ven. Wherever In the armament Galieo
rned his telescope new stars appeared. The
ilky way. which had SO puzzled tho ancients.
rs found to be composed OF stars. His most
illiant achievement was the discovery Of the
ur moons OF Jupiter. His opponents con
nded that there were more than four but no
oof Of the assertion was furnished until last
ar. whom news from the Lick Observatory
adet existence OF a small fifth satellite Of
piter not improbable. 1t should also bs
membered that Calico invented a ther-
ometer and a microscope. II We pass from
s achievements In invention and observation
the 0f |