358 PROCEEDINGS OP THE AMERICAN ACADEMY 



Mr. Safford's mean place with one made from that used in the Nautical 

 Almanac, at the epoch of Dr. Gould's computations, the beginning of 

 the year 1855, and call Mr. Safford's the true and the other the ficti- 

 tious Pole Star, the interval elapsed between the transits of the two 

 stars would be 0^64, and the space between them would be 0".2363, 

 which would represent the difference between the two predictions as it 

 would appear to the eye of the observer. Now a hair of the dimen- 

 sions above given, placed at the distance of 364 feet from the observer, 

 would entirely cover this space, while the same hair, removed to nearly 

 twice this distance, or 665 feet, would cover the space between Gould's 

 Pole Star and Bessel's at the same epoch. If we make the comparison 

 for a date ten years later, the beginning of the year 1865, near the 

 epoch of Mr. Safford's computation, made with the additional data ob- 

 tained in ten years, we find that the difference in the times of predic- 

 tion between Mr. Safford and the Almanac would be about one second 

 of time, and the distance apart of the two stars about one third of a 

 second of arc, which would be completely occulted by a hair at the 

 distance of 233 feet. 



Now if we compare the American Ephemeris place with the British 

 Almanac place for the beginning of the year 1865, which latter place 

 I believe was deduced by Mr. Adams, we find the difference between 

 the times of prediction to be 0^47, and the difference of the phenomena, 

 0".17, would be entirely shut out of view by a hair at the distance of 

 495 feet. Or if there were five Pole Stars that should come to the me- 

 ridian at the different times corresponding to the predictions of Safford, 

 Bessel, Adams, the American Nautical Almanac, and the Berlin Jahr- 

 buch respectively, no meridian instrument with which the Pole Star 

 was ever observed would separate the components of the multiple star 

 which they would form. And if there were two Pole Stars, one in the 

 place assigned by the British Almanac, and the other in that fixed by 

 the American Ephemeris, they would not be separated by any telescope 

 in existence. If they were reduced to the 10th or 11th magnitude, and 

 all circumstances were favorable, and Mr. Clark's great 18-inch glass 

 were used by Mr. Clark himself as the observer, they could not pbssibly 

 be separated ; and the same is true of the Berhn Jahrbuch place. It will 

 thus appear that for all the purposes for which a Nautical Almanac is 

 designed, or for which the Coast Survey may use a star, the place 

 adopted will be found sufficiently near the truth for the present. This 

 star is one of a catalogue of two hundred stars prepared for the use of the 



