THE HAMILTON ASSOCIATION. 67 



manifest themselves at their maximum every 33 years, he says : 

 -'Vast masses of these small bodies move in a long thin stream 

 around the sun, and the earth at stated times plunges through them, 

 taking with its atmosphere each time scores of millions of them. 

 Their orbit is described in 33.i-4th years. They go- out a little 

 further than the planet Uranus, or about 20 times as far as the earth 

 is from the sun. While they all describe the same orbit they are 

 not collected in one compact group, but taking four to five years to 

 pass a given point in the orbit, they may be likened to a train 

 several hundred of millions of miles long, but only a few thousands 

 in thickness. Along with this train travels a comet." Every August, 

 about the loth of the month, there is another star sprinkle, or slighter 

 display of meteors (known among the common people as St. Law-" 

 rence's tears), and a comet, whose period is 125 years, moves in the 

 plane with these meteors, and in a like orbit. Again, early in De- 

 cember there are star showers, the meteoroids composing them tra- 

 velling in the orbit of Bielas' comet. In April slight showers again 

 occur, connected with another comet's orbit. The sporadic meteors 

 of nightly occurrence are but outlying stragglers of a number of me- 

 teoroid streams, and the leading problem of meteor science to-day 

 is to find these streams and their attendant comet. Professor New- 

 ton says the known comets have been apparently growing smaller 

 with their successive returns. Halley's comet was much brighter in 

 its earlier than in its later recurrences. Bielas' comet has divided 

 into two, if not more parts, and has perhaps gone altogether to 

 pieces, as it could not be found in 1872, where it should have ap- 

 peared. The question naturally arises, what causes a comet to break 

 up ? This is yet only a matter of speculation, but this much is 

 known, that comets surely come from stellar space, in whose unim- 

 aginable degree of cold a condensing mass furnished heat for the 

 making of a meteoroid. In cooling, or by some internal convulsion, 

 the mass may break and enter the solar system, either as a mass of 

 pebbles or as one huge body. Nearing the sun, new and strong 

 forces act on it. The same heat and repulsion that develop and 

 drive off from a comet in one direction a tail 100,000,000 miles 

 long, may have worked off and scattered in another direction solid 

 fragments to wander in their own orbit round the sun — an infinitesi- 

 mal comet for millions of years — till entering the earth's atmosphere, 



