164 Prismatic Spectra of the August Meteors. 



example, tlie 10th of August, or the 13th of November), and 

 the attention should be directed below the radiant point, to 

 that portion of the sky where the meteors will, in all proba- 

 bility, appear to fall vertically towards the earth. Near (but 

 not too near) the radiant point, their course is also fore- 

 shortened, and their apparent motion is comparatively slow. 

 Their course in the spectroscope will in this case appear parallel 

 to the refracting edges of the prisms, which is an essential point 

 to be kept in view in the arrangement of the spectroscope, so 

 as to obtain the prismatic spectra of meteors. Some reso- 

 lution, in the next place, is required to fix the attention con- 

 stantly within the stipulated bounds ; for the sky meanwhile 

 is alive with meteors ; and some few are of a startling kind, 

 perhaps even calculated to shake the nerves of any but a cool 

 observer. Paying attention to these precautions during the 

 hours from midnight until sunrise on the morning of the 13th 

 of November next, no difficulty, it is apprehended, of any 

 kind will be experienced in obtaining the spectrum of a shoot- 

 ing-star ; and as the necessity of the case seems to require it, 

 notes should be made of their most peculiar features. 



All the necessary preparations having been made, and with 

 the prospect of a considerable meteoric shower at hand, a 

 watch for meteors was commenced, in order to observe their 

 spectra, on the night of the 9-1 Oth of August last. Expec- 

 tation on the first night was not destined to be disappointed, 

 and six meteors were observed to pass across the field of view. 

 Notes of the peculiarities were made, and of the general 

 appearance of their spectra, and are briefly as follows : — 



August 9th. — No. 1 ; 8h. 40m. p.m. About equal to a 

 fourth mag. star. Passed across the body of Cygnus, in half a 

 second; leaving no streak. The spectrum exactly resembled 

 that of a fourth mag. star (o Cygni) close to which the meteor 

 passed, the conclusion being that the meteor might be a solid 

 body, heated to ignition. 



August 10th. — No. 2; Oh. 27m. a.m. Nearly as bright as 

 Sirius. Commenced near Polaris (in the field of view), and 

 shot 15° or 20° (beyond the field of view) along a line directed 

 from Cassiopeias, leaving a streak on its whole course for four 

 seconds. The latter part of the meteor's course was seen with 

 the naked eye. In the spectroscope two images of the meteor 

 and of the streak were visible, one refracted, and one acci- 

 dentally reflected at the side. These two images of the meteor 

 and of its streak could not be distinguished apart, at least in 

 their general appearance, the conclusion being that the light 

 both of the nucleus and of its luminous streak was homogeneous, 

 and that its luminous substance was a gas. 



No. 3 ; Oh. 42m. a.m. A very brilliant fire-ball, with a flash 



