OBSERVATIONS OF LUMINOUS METEORS. 389 



hour immediately after 2 o'clock a.m., with a sky fairly clear for observations 

 saw not a single meteor in that time. By examining the accompanying 

 diagram, it will be seen that the curves of meteoric frequency, 1, 2, 3, which 

 represent the rates of appearance of the meteors observed by Mr. Lowe, 

 Prof. Grant, and Lord Eosse, all descend towards midnight to the low 

 average of about five meteors per minute for one observer. 



At about the latter hour (corresponding to 6^ 52"° p.m., Washington mean 

 time) the shower first began to be visible in the United States of America, 

 where it was carefully observed by the astronomers at "Washington, by 

 Profs. Newton and Twining at Newhaven, by Mr. Marsh at Philadelphia, and 

 by many other observers for some hours, with a view scarcely obscured by 

 clouds. The following rates of appearance for a single observer are derived 

 (as nearly as such reductions can be made by the convenient table supplied 

 for this purpose by Prof. Newton ; see these Eeports for 1867, p. 412) from 

 the numbers counted by the party of observers at Newhaven, and by Mr. 

 Marsh at Philadelphia ; and the correspondence, if not complete, yet shows 

 that the rate of appearance of the meteors at the commencement of the 

 shower in the United States of America, did not differ very greatly from that 

 observed nearly at the same absolute time in England, when the most long- 

 enduring series of observations there of their decreasing frequency towards 

 midnight were discontinued. 



Approximate numbers of meteors per minute for one observer of the star- 

 shower in the United States of America on the 27th of November, 1872*. 



Newhaven. 



Washington mean time 6'>44'» 54^ 7^4^ IS" 28'° 42'" SS™ S'^IT'" 38" 



Meteors counted per minute... 82 7-7 5-1 4-5 4-4 3-7 37 3-1 2-5 



Greenwich mean time ll'>52'>» 12i»2'" 12"" 23" 36°^ SO-" IS^e-" 25'» 46'" 



Philadelphia. 



Washington mean time 6" 16° 6'' 23-° 37™ 71' 20" 54° ll'>37'» 



Meteors counted per minute. . . 5'5 3 2-5 2 1"5 02 



Greenwich mean time ll'»24'" 11" 31'° 45° 12'»28° 13'>2° 16^45° 



During the height of the shower various maxima occurred, the principal 

 of which were seen by the English observers shortly before 7, and shortly 

 after 8 o'clock p.m., with a less marked maximum between them. The 

 greatest disagreement and uncertainties of the observations relate to the 

 commencement of the shower, which set in and was first begun to be 

 counted during the departing twilight. But as the sun had set nearly three 

 quarters of an hour in Italy, and about an hour and a half at Athens when 

 it disappeared in England, the observations begun at dusk in those more 

 eastern stations supply materials to complete the curve of frequency towards 

 its commencement, which may be more fully relied upon than the imperfect 

 observations made at the same time in Great Britain. In the accompanying 

 diagram, the curves 4 and 5 represent the numbers of meteors per minute for 

 one observer, as recorded in Italy by Padre Denza at the observatory of 



* The times of observation in the first list are the middle points of the periods in 

 which 200 meteors were coimted at Newhaven ; and the numbers of meteors " per minute " 

 are the average rates of frequency in those periods from the numbers coimted in the sepa- 

 rate intervals as stated in the original list, reduced in each case to the number that would 

 have been recorded by a single observer watching for the same interval of time. The 

 numbers in the second Hst are similar average rates for the middle points of the intervals 

 of his watch, as obtained directly from Mr. Marsh's observations. 



