M. Haidinger on the Original Formation of Aerolites. 457 



subject (see Poggendorff 's Annalen, vol. cv. p. 554 et seq.) he calcu- 

 lates there are 4500 meteoric falls per annum, averaging 100 lbs. 

 per fall in weight. Assuming, as we perhaps may do, that he has not 

 materially over-estimated the weight of each fall, he has certainly 

 exaggerated their annual number. Supposing, in the first place, as 

 I believe we may, that detonating meteors are equally aerolitic, 

 whether stones are picked up or not, since most meteoric stones have 

 resulted from a detonating meteor in the first instance, then for the 

 last sixty years, over an area of 900,000 square miles, comprising 

 the countries of Great Britain and Ireland, France, Germany (inclu- 

 sive of Austria, Prussia, Hungary, &c), and Italy, we find recorded 

 (see my " Catalogue of Meteorites and Meteors " in the last volume 

 of the British Association Report for the Oxford Meeting, p. 48) 

 sixty-nine actual stone-falls, and seventy-two meteors accompanied 

 with detonations from which no material residuum was obtained ; 

 say in all 144 cases of aerolitic phenomena. That is about 2^ 

 recorded instances per annum for an area of 900,000 square miles ; 

 and taking the superficial area of the whole globe at 197,000,000 

 square miles, we obtain rather over five hundred falls (511) as the 

 number likely to be observed, were all the world covered by land and 

 peopled in like manner by Europeans. 



Now, what proportion this number would bear to those that abso- 

 lutely do fall annually, but which are never noticed or not recorded in 

 scientific works, it is not very easy to say ; but from various reasons 

 it may be fairly estimated at more than half of the entire number. 

 Chladni and Humboldt have estimated the total number at 700. 



There are several reasons for inducing us to increase the annual 

 number of observed and recorded falls, viz. 500, to 800 or 900, as the 

 actual number that fall, and not more. First, the fact that one-half 

 the human race are supposed to be asleep or in their houses nearly 

 twelve hours out of the twenty-four, must tend to limit considerably 

 the number of observations ; on the other hand, we are not without 

 instances of stone-falls and other aerolitic phenomena, detonating 

 meteors more especially, occurring during the night-time ; while again, 

 as I have shown in the tabulated results of my large Catalogue, p. 1 18, 

 the greatest number of stone-falls seem to occur in the afternoon 

 about 4 o'clock, not only as against falls taking place during the 

 night, but as compared even with the corresponding hours in the 

 forenoon, equally favourable as a time for such observations. Though 

 stones have not frequently been picked up during the night-time, we 

 may bear in mind that the night is a most favourable time for seeing 

 large and brilliant aerolitic meteors, and that the darkness does not 

 prevent us from hearing the violent detonations usually accompany- 

 ing the explosion of an aerolitic meteor. Then, again, it is not 

 unusual for an aerolitic meteor to pass overhead some hundreds 

 of miles, and for the detonation to be heard over from twenty to 

 forty miles square ; and some persons would probably notice one or 

 the other. Now as I have included as aerolitic, meteors from 

 which no stones have been picked up, it will I think be admitted 

 that to double the entire number of both classes actually recorded 

 Phil, Mag, S. 4. Vol. 22, No. 149, Dec, 1861. 2 H 



