Morning journal and courier., 1892-03-16
THE MECHANICS, COURSE.

Professor Newton Discourses on the
 stCapture of Comets by JuPiter''-
 only Two More Lectures In she
 Course.
 Professor Newton lectured before 8 large audience last evening in North Shelf field hall on the Capture of Comets by | Jupiter" It was very interesting and | instructive lecture. There are only two more lectures in the course, viz.: "Uni- l versity Life in Germany" Professor Stevens, and ssThe Natural History of the. American Oyster and It's Enemies," Pro- lessor Verrill.
 As introducing what wish to say to- night said Professor Newton, let ma re- call to your minds @ few facts as to the
 structure of the solar system. To many l of you these facts are familiar, but you
 will surely excuse me, inasmuch as to
 some of you it will be . convenience to
 have them called to mind. Pointing to
 diagram of the solar system the professor
 said: The sun, as you see, is by far the
 largest body, being several hundred times
 as large as all the rest put together. Of
 the rest Jupiter is the largest. There are,
 however, four large planets, Jupiter, Sat
 urn, Uranus and Neptune. Their com
 bined weight is about 1.70O that of the
 sun, and for our purpose tonight the
 weights are more important than the
 bulks.
 II The earth's mean distance from the sun
 Is the measuring-rod in the solar system.
 Jupiter's distance in round numbers is 5,
 Saturn's is 10, that of Uranus Is 20, Nep- tune 30. These planets all move around
 the sun In orbits which are nearly circles and which lie very nearly in one plane.
 Now, the comets move around the sun in any direction, some coming down from
 the north pole, others going up from the
 south pole. The orbit in which any comet or planet must move about the sun is we'll l known to be one of the comic sections.
 The planets are said to move in circles, but really move in ellipses.
 We never see @ comet except when it is
 very near the sun. Very rarely has a that of Jupiter. Now, there is funda- | mental law in nature called the law of con- servation of energy. It is that law which . l makes what is called g perpetual motion l machine impossible-that is, machine D which does work without using energy a from some source. According to that law
 the comet loses by the sun's attraction
 while reeeding from the sun, exactly az
 much velocity as it gained thereby in ap j. preaching the sun. I have said that the d comets in general move in any direction .- about the sun. There is, however, a pc culiar group of small comets that must be " regarded as an exception to this rule These comets have short periods and a 7. the same time they move about the sun il 'f the same direction as the planets Beside y these comets there are several hund rec ts others moving in longer orbits than thes n and constitute the greater bulk of thi
 class of bodies in the solar system. An i'm
 portant question has arisen: Have thes short period comets been drawn in tn o solar system by the action of Jupiter as Would Jupiter in turning comets into tn n solar system give them this peculiar diree motion and small inclinationf A carefu study of the action of Jupiter upon bodie .n coming nearer him leads to an afarms ls tive answer to this question and we ar 10 able to say with great positiveness that 9o te Jupiter should change large number m comets from long orbits inclined g Ill all angles to the plans of Jupiter ID ID orbit would become comets of sho1 Ie period. So as to be permanent membe y of the solar system we ought to expect tha
 these comets should in general move wit
 direct motion and small inclination; i
 other words, that precisely that conditio i- of things which we find to be existing i pr the solar system would naturally be pro III duced if the short period comets ha
 originally been moving like a great mas nv of comets in all directions about the SUI " All these causes combine and work tt LII gether to the end that those comets whic
 are changed by the perturbing action C g. Jupiter or other planets change from par' 1n Se bolic orbits of every possible inclinatio he to the ecl1pGlc Into the short period elhpst ne and thus become permanent members the solar system. As rule (but with e1 he ceptions) they move in orbits of moderat a inclination to the ecliptic and with dire. L. 1 motion