348 The Variable Star Algol. » Fy 
served, reduced to mean Paris time by applying the difference of 
longitude ;—the third indicates the observer; B. denoting Mr. 
Bruhns in Berlin; H., Prof. Heis in Miinster; N., Dr. Nell in 
Manheim; O., Dr. Oudemans in Leyden; Sd., K., and A., Dr.» 
Schénfield, Dr. Kriiger and the author in Bonn. The fourth 
column contains the equation of light, and is that quantity which 
is to be added to the observed moment in order to correct it for 
the difference of time which, in the different distances of the 
stars from the earth, is required for the light to reach us. Finally, 
the fifth column gives the time, reduced to the principal epoch. 
o obtain from these numbers the most probable result, we 
should not take the mean directly, but if a@ denote the probable 
irregularity of the period, and & the probable error of observation, 
each one of the n observations of the same minimum will receive 
the value 1: (na?+6?). But since, as we have already seen, a? 
is at any rate very small in comparison with 62, and the number 
of observations yet too small to determine a with any degree of 
accuracy, the simple mean will still afford the most trustworthy 
result. This is, for the epoch 6976, Oct. 8, 5% 30™ 27:0 M. T. 
Paris. The period might, according to the table already given, 
be assumed for the next year as about 24 204 48™ 5155. B 
since the above result for Ep. 6976 compared with that which 18 
observations furnish for Ep. 6870, namely, 1853, Dec. 8, 72 7™ 2456 
M. T. Paris, gives the decidedly longer period 24 20% 48™ 53°8-+ 
1s-04, I have, in computing the following table of minima for the 
year 1855, combined the period 24 20% 48™ §2s with the epoch for 
1854, Oct. 8. According to this, the first minimum of the year 
occurs Jan. 2, 08 38" 57s M. T. Washington, and the subsequent 
ones which occur in the hours of darkness, are stated below, an 
already corrected for the equation of light, so that the time for 
observation is directly given. 
Minima of Algol visible in America, 1855—WasHINGTON MEAN TIME. 
h. m.} h. m. | h. m. h. mn. h. m.| h 
Jan, 7 1813 Feb. 32 15 19 July 1 16 "SlAug. 22 6 S71Oct. 15 17 59 Nov. 30 15 
1015 1} 2512 8 4 1252/Sept. 21749] 18 1449Dec. 3114 
13 1150 5 41 1438; 21 21 36, 6 8 
16 8 40 Mar. 17 1354 24 1431 1127 24 825 9 dl 
19 529) 20 10 43 27 11 20 11 816\Nov. 7 1629 page= 
| roe 30 8 9 25 16 19 10 13 18 pears 
Feb. 2 1335 Apr. 12 9 16/Aug. 13 16 11 2313.7] 1310 7 aaah 
5 1024 May 19 1552 16 1259|Oct. 9 56 29:7 
_ 8 713 June 11 14 22 19 948 4 645 27 18 11 
Bonn, 1854, December 9. 
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