98 REPORT — 1864. 



in grains, and the latter pretty large. The crust is one-fiftieth of an inch 

 in thickness, and duU black. 



A stone of 2| ozs. is in the Museum of Mineralogy at Vienna, 2^ lbs. in 

 the Museum of Natural History at Paris, and a fragment, 1 lb. in weight, in 

 the British Museum. 



(4.) 1864, March 14th, and 1864, May 2nd. 



"May 8tJi to 14th is an aerolitic period, and its radiant-point should he 

 determined." (E. P. Greg, Manchester, 14th March, 1864.) 



" May the 12th xvill he the next time to verify, and has of late years heen 

 very richly aerolitic." (P. P. Greg, Manchester, 2nd May, 1864.) 



The aerolitic period so defined by Mr. Greg was verified by the fall of a 

 meteorite at Orgueil (S. France), on the evening of the 14th May, 1864. 

 The meteorites are rich in carbon and soluble salts, among which are those of 

 ammonia. (Comptes Rendus, vol. Iviii., for May 23, and following numbers 

 contain full particulars. At pp. 1100 and 1212 the trajectory of the meteor 

 is described.) 



YI. EADIANT-POUfTS OF ShOOTINS-STAES. 



Showers of meteors are of comparatively frequent occurrence, and, since the 

 display of November 1833, it is well kuo'mi that the meteoric tracks on these 

 occasions take their directions fi-om a point (termed the radiant- jioint of the 

 shower) which retains its apparent place imchanged among the stars during 

 the continuance of the shower. The following observations were expressly 

 condiicted for the purpose of determining the radiant-points of meteors on 

 particular dates, since the last Eeport : — 



Date of Approximate No. of General Accuracy 



Observation. Position of Radiant-point. Observations. of Divergence. 



R.A. N.Decl. 



1863, Aug. 10-11.../.- Persei 43-8 56-2 120 ... Great. 



,, Dec. 12-13. ..r Geniinorum . 105'5 30'5 17 ... Considerable. 



1864, Jan. 2-3 ...e Quadrantis... 234-0 50 9 100 ... Great. 



„ Apr. 10-11...5Virginis 1923 4-2 12 ... Average. 



„ Apr. 12-13. ..Cerberus 270-0 250 16 ... Inconsiderable. 



„ Apr. 19-20. ..near a Lvrsc... 277-5 34-6 23 ... Great. 



„ Aug. 9-10...D Camelopardi 49-8 55-0 87 ... Considerable. 



The position of the radiant-point on the night of the 2nd January differs 

 only 5° from the centre of eight very luminous excursions, observed by the 

 late Stillman Masters, in America, at davbreak on the 2nd Januarv, 1863 

 (E. A. 23S°-0, N. P. D. 43°-6). The fixity of this radiant-point for two suc- 

 cessive years, under circumstances so widely difi'cring from one another in 

 hour and place, is a strong aVgument for the astronomical uatiu'e of periodical 

 meteors. A radiant-point near a Lyra; was observed in America, by the 

 late E. C Hen-ick, on the morning of the 19th April, 1839, a qiuirter of a 

 century before the observation recorded in this list. Eelying upon the gene- 

 ral stability of meteoric phenomena, it is possible to determine the radiant- 

 points of sjjoradic meteors (if these exist), in the same manner as the radiant- 

 points of periodical shooting-stars, from observations of a long series of years. 

 The Eeports of the British Association, Coulvier Gravier's Catalogues, and 

 • other less extensive observations atford more than sufficient materials for the 

 purpose. The centres of excursion of sjioradic meteors continue for weeks, 

 or even months, in one position, until theii' epochs overlap. Two or more 

 centres of excursions then coexist for a time, and afterwards give place to 

 other radiant-points. The following list of general radiant-points of shootings 



