Royal Astronomical Society. 553 



their great altitude and brilliancy are visible over considerable por- 

 tions of the earth's surface, would afford excellent natural signals, 

 provided they could be identified with certainty, was an obvious 

 thought ; but so long as they were regarded merely as casual phe- 

 nomena, it could scarcely be hoped that they would be of much use, 

 in this respect, to practical astronomy. As soon, however, as their 

 periodicity became probable, the observation of the phenomena ac- 

 quired a new interest. In observing the meteors for this purpose, 

 it is assumed that they appear instantaneously to observers stationed 

 at a distance from each other, and that the meteors seen by different 

 observers so placed are identically the same. These points are not 

 altogether free from uncertainty ; but the results of the trials that 

 have been already made may be regarded as favourable, and as 

 showing that among the other methods of determining astronomical 

 positions, the observation of shooting- stars is not to be disregarded. 

 At the November meeting of this Society, in 1839, an account was 

 given of Professor Schumacher's observations at Altona on the 

 night of the 10th of August, 1838. On the same night, corre- 

 sponding observations were made at several observatories in Ger- 

 many ; but those at Breslaw appear to have been the most success- 

 ful. From twelve coincident observations at Altona and Breslaw, 

 Professor Boguslawski computed the difference of longitude of the 

 two places to be 28 m 22 s- 07, which differs less than a second from 

 that which had been previously adopted. In Silliman's American 

 Journal for October 1840, an account is given of simultaneous ob- 

 servations made on the 25th of November, 1835, at Philadelphia, 

 and at the College of New Jersey, at Princeton. Seven coincidences 

 were observed, and the mean result gave a longitude differing only 

 l s, 2 from the mean of other determinations ; the whole difference 

 being two minutes. This appears to have been the first actual de- 

 termination of a difference of longitude by meteoric observations. 

 In the corresponding observations of Wartmann and Reynier at 

 Geneva and Planchettes, the differences of longitude deduced from 

 three of the meteors, which were attended with peculiarities so re- 

 markable as to leave no doubt of their identity, were respectively 

 2 m , 2 m 3 s , 2 m 5 s , whence it would seem that a single observation 

 may be in error to the amount of several seconds of time. In the 

 Bibliotheque Universelle de Geneve for August 1840, there is given 

 an account of the determination by this method of the difference of 

 longitude between Rome and Naples. The corresponding observa- 

 tions were begun in November 1838, and were continued at inter- 

 vals under the direction of Father Vico at Rome, and of Capocci and 

 Nobili at Naples. The apparent paths of the meteors were traced 

 on a celestial globe, and the times of appearance and extinction 

 compared with clocks regulated by astronomical observations. The 

 observed times of the extinction of the phsenomena presented a very 

 satisfactory agreement, inasmuch as it is stated that there was in 

 general a difference of only a few tenths of a second of time between 

 the partial results for a difference of longitude amounting to 7 m 5 s * 7. 

 The merit of first suggesting the use of shooting- stars and fire- 

 PhiliMag. S.3. Vol. 19. No. 127. Suppl. Jan. 1842. 2 O 



