548 Royal Astronomical Society* 



miles in length, and stationed themselves at its extremities, they 

 began to observe on nights previously agreed on; and when a me- 

 teor was seen, they immediately traced its apparent path on a ce- 

 lestial map, noting carefully the exact times of its appearance and 

 extinction, with any other circumstances likely to assist in identify- 

 ing it. The meteors observed simultaneously at both stations were 

 in this manner recognised with considerable certainty ; and the com- 

 parison of their paths on the two maps afforded data for the deter- 

 mination of their parallaxes and altitudes. The results were as fol- 

 lows : — Between the 11th of September and the 4th of November, 

 1798, only twenty-two corresponding observations were obtained 

 from which the altitudes could be computed. The altitude of the 

 lowest was about six English miles ; there were seven under 45 

 miles ; nine between 45 and 90 miles ; six above 90 miles ; and one 

 had an altitude of about 140 miles. There were only two observa- 

 tions from which the velocity could be deduced : the first gave 25 

 miles, and the second from 17 to 21 miles in a second. The most 

 remarkable result was, that at least one of the meteors moved up- 

 wards, or away from the earth. By these observations, the perfect 

 similarity between fire-balls and shooting- stars, in respect of velocity 

 and altitude, was completely established. 



Another attempt, on a more extensive scale, to determine the al- 

 titudes and velocities of shooting-stars by means of simultaneous 

 observations, was made by Brandes in 1823, assisted by a number 

 of associates resident in Breslaw and the neighbouring towns. The 

 observations were continued from April to October, and during this 

 interval about 1S00 shooting-stars were observed at the different 

 places, out of which number ninety- eight were found which had been 

 observed simultaneously at more than one station. The altitudes of 

 four of these were computed to be under 15 English miles ; of fifteen 

 between 1 5 and 30 miles ; of twenty-two between 30 and 45 miles ; 

 of thirty-five between 45 and 70 miles ; of thirteen between 70 and 

 90 miles ; and of eleven above 90 miles. Two of these last had an 

 altitude of about 140 miles ; one of 220 miles ; one of 280 miles ; 

 and there was one whose height was computed to exceed 460 miles. 

 Thirty-six orbits were obtained ; in twenty-six of which the motion 

 was downwards, in one horizontal, and in the remaining nine more 

 or less upwards. In three cases only the observations were so com- 

 plete as to furnish data for determining the velocity ; the results 

 were respectively 23, 28, and 37 English miles in a second, the last 

 being nearly double the velocity of the earth in its orbit. The tra- 

 jectories were frequently not straight lines, but incurvated, some- 

 times horizontally, and sometimes vertically, and sometimes they 

 were of a serpentine form. The predominating direction of the mo- 

 tion was from north-east to south-west, contrary to the motion of 

 the earth in its orbit,: — a circumstance which has been generally re- 

 marked, and which is important in respect of the physical theory of 

 the meteors. 



A similar set of observations was made in Belgium in 1824, under 

 the direction of M. Quetelet, the results of which are published in 



