32 The Solar Eclipse of August last. [Jan., 



the case of the Burlington party, all went smoothly, and the dark 

 weather alone prevented final adjustment until the night of the 6th, 

 or morning of the 7th, when this was secured by Professor Mayer, 

 who sat up all night for the purpose. 



With the Ottumwa instrument it was, however, found that the 

 clockwork had become seriously deranged in carriage, so that Mr. 

 Zentmayer was obliged to take it entirely apart and refit it. The 

 final adjustment was only given to this instrument during the 

 morning of the 7th by Mr. Zentmayer, who had watched all night, 

 vainly, for a star. 



The telescope at Mount Pleasant having no clockwork, and being 

 otherwise unfit for any fine adjustment, required no arrangement 

 except what could be given during the morning of the 7th. 



The weather on the eventful day of the eclipse was at all sta- 

 tions perfect, thus rendering needless the policy of distribution, and 

 no less than 116 negatives were taken, including 13 during totality, 

 showing a large number of prominences, some massive and others 

 delicate as well as radiant brushes of a softer light, such as have 

 been before seen, but never as yet photographed. By another of 

 the sections of this large party, beside similar pictures to the above, 

 one was obtained showing the curious phenomena known as Baily's 

 beads, being simply the last glimpse of the sun's edge cut by the 

 peaks of lunar mountains into irregular spots. The time of expo- 

 sure determined by Professor Mayer for the partial-phase pictures 

 was the -^th of a second. Those taken during totality were 

 exposed from five to sixteen seconds. 



The general character of the prominences will be seen by the 

 coloured illustration, which has been excellently copied from the 

 original photographs and micrometric measurements forwarded to 

 us by Professor Morton. The dotted circle inside the circumfe- 

 rence of the moon, shows the relative diameter and position of the 

 sun at the middle of the total eclipse. The accompanying woodcut 

 may be regarded as a key to the coloured picture, and will serve to 

 facilitate the following description of the phenomena : — 



The line a b represents the direction of a parallel of declination. 

 c d a declination circle, r e is the moon's path from first contact 

 at f. The prominences are here all shown at once ; although, of 

 course, those on the sun's eastern limb alone were seen at first, those 

 on the west side only at the end of the totality. Proceeding from 

 the north to the east, we first meet with a small prominence having 

 the position angle of about 56° 30'; it is of the shape of a rice 

 grain, with its base but slightly below the circumference of the 

 moon. In breadth it is 2° 50', and in height 22" ; as 1' on the cir- 

 cumference of the sun equals 124 miles, and 1" of arc of the sun's 

 distance on August 7th subtends 449 miles, it follows that its 

 actual dimensions are 21,000 miles long and 9900 miles high. 



