OBSERVATIONS OF LUMINOUS METEORS, 



29 



simultaneously observed until the beginning of that year. The average 

 velocity of the Perseids, relatively to the earth, observed in the year 1863 

 was 34-4 miles per second, and that of the three Perseids satisfactorily well 

 observed in the present list is 37 miles per second. In his original letters to 

 Father Secchi on their connexion with Tattle's comet (Comet III., 1862), 

 now universally accepted as a true basis of their cosmical theory, Prof. 

 Schiaparelli calculated, from the known elements of the comet's orbit, that 

 the velocity with which the Perseids enter the earth's atmosphere (allowing 

 for a very minute influence of the earth's attraction) is 38 miles per second. 

 That the direct determination of the velocities of the August shooting-stars 

 which were made last year should, in this instance, so exactly agree with the 

 value found by calculation (although from the small number of identifiable 

 meteors the probable error of the determination is rather large), is, from the 

 great scale and general excellence of the observations, at least provisionally, 

 a successful confirmation of the astronomical theory of the August meteors, 

 and a satisfactory conclusion from the simultaneous watch. 



2. During the corresponding observations of the meteor-shower of No- 

 vember last, in which the observers of Mr. Glaisher's staff at the Eoyal 

 Observatory, Greenwich, also took an important share, the coincidence of 

 the times of appearance and of the other particulars of a single meteor only 

 of the shower simultaneously observed at Greenwich and at Tooting, near 

 London, could be established, the descriptions of which, as given by the 

 observers at those stations, were as follows : — 



The apparent paths of the meteor among the constellations present a con- 

 siderable parallax in the right direction of displacement, as seen from the 

 two observers' stations, to lead to a positive determination of its real altitude 

 above the earth. The concluded path of the meteor is nearly horizontal at 

 a height of about fifteen miles above the earth's surface. The small distance 

 (only seven miles) between the two stations, greatly increasing the effect of 

 the errors most difficult to avoid in the observation and description of such 

 transitory phenomena, must, however, for the present be regarded as pre- 

 cluding certainty from the conclusion, which would otherwise attach to this 

 unusually low elevation of a meteor's real path. 



