OBSERVATIONS OF LUMINOUS METEORS. 343 



read to the Royal Astronomical Society* in Jannary and April last, on 

 the long-observed duration of some meteor-showers, with stationary 

 radiant-points. That the centres of divergence of ordinary shooting- 

 stars in general ocenpy almost fixed positions in the heavens for several 

 days, or even weeks, together, is indeed conceded by nearly all the observers 

 who have recorded and discussed their radiant-points. But a much 

 more strange and extraordinary peculiarity of these showers was believed 

 to have been noticed by Mr. Denning, that after a first appearance, or 

 period of prevalence of an ordinary meteor- shower, followed by a lull, 

 or interval of entire cessation of its action, a radiant-point will again 

 make its appearance with renewed activity, forming apparently, a repeti- 

 tion of the original meteor-shower in everything except its date, at an 

 interval of about three months after its first display. Examples of such 

 recurrences were traced by Mr. Denning, between August-September and 

 October-December, between October-December and February-April, and 

 between April-May and July- August meteor-showers. The end arrived at 

 hitherto, by continued observations, has been to multiply ceaselessly the 

 number of new radiant-points, and to discover sub-showers, as tributary 

 streams in systems which had formerly been held to be thoroughly well 

 isolated and defined. The multiplicity of radiant-points which thus accu- 

 mulate from year to year, are chiefly congregated near the meteor-epochs, 

 of August, November, and April, when it is not unreasonable to expect, 

 from the numbers which have been recorded, and from the attention 

 naturally concentrated upon well-known regions of the sky, that fre- 

 quent repetitions of radiant-points, at intervals of about three months 

 should, in general, be traceable in different seasons of the year. The 

 slenderly supported evidences of connection between cometary and 

 meteor-shower radiant-points, in a multitude of cases where they very 

 nearly approach each other, is an indication how much chance may have 

 to do with frequent occurrences of such an apparent resemblance, even 

 between contemporaneous radiant-points, and in a list of cometary 

 radiant-points, not unfrequent instances may be selected of recurrences 

 of identical positions, with periods of one or two, and sometimes of 

 three or more, months intervening between them. The theoretical 

 grounds on which the hypothesis of trimestral meteor-showers is shown 

 to be untenable, were clearly urged, in some apposite remarks appended 

 to Mr. Denning's paper, by Captain Tupman ; and, indeed, no deep 

 acquaintance with Physical Astronomy is required, to show that, even if 

 it should be indubitably established by further observations and re- 

 searches, no such hypothesis could be derived directly, in the present 

 state of the science of astronomical perturbations, from any supposed 

 primitive relation of the orbits or assumed remote or recent origin of 

 scattered and diffuse, or of still compact and undisintegrated meteor- 

 showers. 



Of the circum-Perseid showers of August 6th-12th, Mr. Denning also 

 prepared a list, by pi'ojecting numerous meteors of the periodic dates in 

 the catalogues of the Italian observers (1872), Heis (1852-72), and von 

 Konkoly (1871-7G). The positions and numbers of meteors belonging to 

 each radiant, as collectively determined by one or more of those three 



* Monthly Notices of the Koyal Astronomical Society, vol. xxxviii., pp. 111-116, 

 and 351. 



