628 OLIVER C. FARRINGTON 



into the form of a somewhat attenuated swarm or cluster. The 

 possibility of the subsequent capture of single portions of such 

 a cluster by the earth can hardly be denied. The character of 

 the portion captured, in respect to its structure, density, and 

 composition, then, will depend on the position it occupied in 

 the globe of which it formed a part. 



That meteorites exist in such swarms in space seems very 

 probable from a recent investigation of Hogbom,"^ Plotting the 

 known meteorite falls according to the days of the year, he has 

 discovered undoubted and significant groupings. Thus of the 

 nine known howardites, three fell during the first days of 

 August, and three during the first half of December. The 

 probabilities are stated to be several thousand to one against 

 such an occurrence being- a mere coincidence. Again, of the 

 three known eukrites two fell June 13-15. The chances are said 

 to be ninety to one that these had a common origin. There 

 are numerous other groups brought out on the chart so made, 

 which seem to point to the existence in space of meteorite clus- 

 ters met on the same date by the earth in its annual revolution. 

 The probabilities seem sufificiently in favor of the existence of 

 such clusters to warrant placing some reliance in the constitu- 

 tion indicated for them. Thus with the group of August howard- 

 ites previously mentioned are associated one siderite and three 

 chondrites; with the December howardites, one siderite, one 

 bustite, one chladnite, and a number of chondrites. The consti- 

 tution indicated for these swarms resembles therefore, to a 

 remarkable degree, that called for by the hypothesis here 

 advocated, especially when it is remembered how exceedingly 

 fragmentary must be evidence based on the few meteorites seen 

 to fall. A similar constitution has been also exhibited at times 

 in the substance of a single meteoric shower. A notable case 

 is that of Estherville, which contained all gradations, from iron 

 to stone meteorites. 



Two or three other points of evidence may be noted as tend- 

 ing to show that, in such a globe as that assumed, the substances 



' Bull. Geol, Inst, of the University of Upsala, Vol. V., Part i. 



