and Astronomical Notices. \%V 



proved whether they be solar or lunar prominences ; and this 

 is to be done by taking measures as rapidly, but as exactly, 

 as possible, of their number, size, form, and position, imme- 

 diately after the commencement of the tjotality of the eclipse, 

 and again immediately before its termination. If there should 

 be many of them, an observer in the middle of the line of the 

 shadow should confine himself to those which appear in the 

 direction of the moon's path across the sun ; while an obser- 

 ver at the limit of the shadow should restrict his attention to 

 those at right angles to that line, and should then compare 

 his observations with similar ones made by another person 

 at the opposite limit. To make this comparison effectual, all 

 determinations of size or position should be measured instru- 

 men tally in terms of space, and nothing should be left to 

 mere idea and fancy. A rude position-micrometer, with a 

 coarse screw, and an easy, quick method of reading off divi- 

 gions and revolutions might be the best tool to use, if the^ 

 telescope be mounted on a stand having parallactic motion ; 

 one screw would probably be enough, and the wires should 

 be very thick, so as to be easily seen without illumination, 

 but a lamp might be as well provided, both to guard against 

 the possibility of the wires not being seen, just at that pecu^ 

 liar instant when they are most wanted, and also for facility 

 of writing down the numbers. In default of this apparatus, 

 the eyepiece might be provided with a network of wires in 

 squares, and measures made in terms of those visible quan- 

 tities. In either case, some practice should be taken before- 

 hand in doing quickly and neatly what may be expected wilL 

 have to be done on the occasion. Combined with the above 

 must be measures, before and after the eclipse, of any light 

 or dark spots, or anything peculiar, which may be seen on the 

 sun's surface. 



At the same time other persons should be on the watch 

 for the zodiacal light, that vast nebulous member of the solar 

 system, of which we can at other times distinguish only the 

 fainter extremities, but may during the totality witness the 

 denser central portions, and so ascertain, whether it be a , 

 ring round about and at a distance from the sun, or a lenti- 

 cular body having the sun in its densest part. This im- 



