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



with beautifully coloured drawings showing the rapid changes 

 which sometimes occur 4n the forms of these prominences even in 

 the course of a few hours. Observing one of the most remarkable 

 formations, the Professor says, " I hardly believed my eyes when I 

 noticed in it the tongue-like motion of a flame. This motion was 

 slower, however, compared with the size of the flame than that of 

 high towering flames at great conflagrations. The time required 

 by such a wave in passing from the base to the apex was about 

 two or three seconds." 



In comparing the general impression of the protuberances with 

 terrestrial phenomena, the author states that the great majority 

 remind him of the different forms of our clouds and fog. The 

 cumulus type is completely developed in the cases here referred to. 

 Other formations remind us of masses of clouds and fogs floating 

 closely over lowlands and seas, whose upper parts are driven and 

 torn by currents of air, and which present the well-known, ever- 

 Tarying forms when viewed from the tops of high mountains. 



Professor Zollner hopes, by using larger prisms and a circular 

 slit in the spectroscope, to be enabled to observe simultaneously all 

 the protuberances on the edge of the sun, in the different parts of 

 the spectrum, just as in a total solar eclipse of long duration. 



Eeturning to the August eclipse, one of the most beautiful 

 otservations was on the first contact by means of the spectroscope. 

 Professor Young has been giving much attention to this subject, and 

 had fitted up a very efficient instrument for the purpose. The instru- 

 ment consisted of a spectroscope with five prisms of 45° each, having 

 faces 2J by 3 J inches ; the collimator and telescope had apertures of 

 2£ inches, with a focal length of 17. These were connected with a 

 ccmet-seeker of 4 inches aperture and 30 inches focus, used with an 

 eye-piece, and giving an image of the sun 2J inches in diameter on 

 the slit of the spectroscope. A graduated screen at the slit determined 

 positions of points on the sun's limb, and a wire micrometer measured 

 the positions of spectrum lines. The whole was mounted equatorially 

 with slow-motion screws. During the eclipse he was stationed at 

 Burlington, Iowa, and shortly before the first contact was due, he 

 found that there was a solar prominence located at the spot where 

 first contact must occur (see f in cut on page 33). He therefore 

 fixed his spectroscope with the slit radial to the solar edge at the 

 point, so getting a prominent spectrum whose width was determined 

 by the height of the prominence. Closely watching this, he pre- 

 sently found that it began to narrow steadily, and at the instant 

 that it became a mere fine and disappeared he recorded first contact. 

 The moon's approach was perceived full 30" before its actual ap- 

 pulse ; the observation was perfectly easy, and the time determined 

 is certainly to be relied on within half a second, and probably much 

 less. The presence of a prominence at the point of contact is not 



