148 



REPORT — 1877. 



nearly the same hyperbolic orbit round the sun, becomes at once a very 

 probable and a new and remarkable conclusion from these very exact recent 

 observations*. 



* A case of probable coincidence of orbits of two aerolites is noticed by Prof. Kirkwood 

 in ' Nature,' vol. xiv. p. 526 (Oct. 12, 1876)— those of Meno (Mecklenburg, 1861, October 1 , 

 12 h , noon), and one named by Dr. Lawrence Smith after its donor, Mr. Claywater, who 

 described its fall (in Vernon Co., Wisconsin, U.S., 1865, March 25, 9 h a.m.), having been 

 recently shown by Dr. Lawrence Smith (Amer. Journ. of Science, September 1876) to be 

 almost identical in their composition, as if fragments of one and the same very unusually 

 constituted meteorite. Reckoned on the ecliptic the dates of their fall are 183° or 177° 

 apart in longitude, greatly favouring the supposition that in some conic section, the incli- 

 nation of whose plane to that of the ecliptic is not necessarily restricted, these two bodies 

 may have been pursuing one and the same astronomical orbit round the sun, whose perihe- 

 lion (if it exists) must evidently lie midway (in longitude 97° or 277°) between the two 

 points of the earth's encounter with the meteorites. Supposing, however, that no very 

 sensible inclination of the orbit plane to that of the ecliptic should exist, the condition 

 either of conjunction or of opposition (or of a six months' interval between the dates) of two 

 meteoric occurrences is not a necessary condition to their belonging to a common circum- 

 solar orbit ; and Prof. Kirkwood mentions the great similarity of composition between the 

 meteorites of Somer Co., U.S. (May 22, 1827), and Utrecht, Germany (June 2, 1843), re- 

 marked by Baumhauer, which, if these meteorites were pursuing the same orbit, would 

 oblige us to suppose it to have had two intersections with the earth's orbit very near to- 

 gether, and to have therefore had either no sensible or at least only a very small inclina- 

 tion to the ecliptic. As regards the probable inclination of the Meno-Wisconsin pair of 

 strongly resembling meteorites, a very simple consideration of the aspects of the horizon 

 with regard to the sun and to the apex of the earth's way at the times and places of the 

 two aerolitic falls (which were very analogous to each other at the two places) shows that 

 the perihelion of the common orbit (if it was nearly parabolic) must have had southern 

 latitude, lying somewhere on an arc included between long. 97°, S. lat. 5°, and long. 277°, 

 S. lat. 45°. If with this southern perihelion the descending node of the orbit was at Meno 

 (in ecliptic longitude 8°) and the ascending node was at Vernon Co. (in ecliptic longitude 

 185°), the meteorites' real courses must have been from a low altitude in the north or 

 north-west at Meno, and from a low altitude above the south to east horizon in Wisconsin. 

 If the reverse was the case, and (he ascending and descending nodes of the meteoritic 

 orbit were respectively at Meno and Vernon Co., the meteorites must have come from very 

 near the south- and north-western horizons of those two places ; but on neither of these 

 two hypotheses have any cometary orbits been recorded which come even roughly within 

 the wide limits of the requirements established by these astronomical conditions. These 

 are summed up in the following table of the orbit elements necessary to satisfy the known 

 circumstances of the aerolitic falls, and the elements of the comets of 1264 (and 1556), 

 which among several such apparent resemblances entirely fail of satisfying them, are 

 added for comparison in the Table. 



Meno-Claywater 



Meteorites and 



Comets. 



Longitude 

 of a. 



Radius vector 



of orbit (®'s 



rad. vect. = l). 



Stonefall,inWis- ) 

 consin, from V 

 north-west. J 



Stonefall.inWis-] 

 consin, from I 

 south-east. J 



Comets 1264 

 (and 1556) ; 

 (equinox of \ 

 1860). J 



185° 



184° 



100 



100 



098 



Motion. 



Long, of 

 perihelion. 



Inclination. 



Retrogr. 

 Direct. 



Direct. 

 Retrogr. 



Direct. 



97° 



277° 



97° 



277° 



281° 



Latitude of 

 perihelion. 



between 5° 

 and 90° 



between 90° 

 and 45°. 



between 45° 

 and 90° 



between 90° 

 and 5°. 



30° 



5° to 90° S. 

 45° to 90° S. 



45° to 90° S. 

 5° to 90° S. 



29°-5 N. 



The perihelion of the orbit of the comets 1264 (and 1556) is north of the ecliptic, as 

 are also all those of the comets (of A.i>. 178, 1580, 1683, and 1763) which otherwise appear 





