548 



Progress in Science. 



[October, 



was painted, supported so as to rotate on its axis and admit of various incli- 

 nations. This was placed as an " objedt " in a large oxyhydrogen lantern, in 

 front of a circular orifice representing the solar disc. The effect upon the 

 screen was remarkably good. To imitate the formation of solar protuberances, 

 a glass tank, provided with a coil of platinum wire, was likewise introduced 

 in the lantern and filled with water, at the bottom of which was a little solu- 

 tion of cochineal. The coil being heated by the current from a single " flask" 

 battery, a stream of the crimson cochineal solution was thrown up, and as- 

 sumed from time to time various forms, some of which bore a striking resem- 

 blance to the figures of solar prominences which have been figured by Young, 

 Lockyer, Respighi, and others. Again, to illustrate the various phenomena 

 of a solar eclipse, an apparatus was employed whose construction and opera- 

 tion can be explained by the aid of the accompanying figure. To the further 



Fig. ■;. 



side of the frame, a b, is attached a plate of glass on which is painted or 

 photographed a pidture of the sun's disc, with the " flames " and corona. 

 These are, of course, bright on a dark ground. Next, in front of this, slides a 

 plate of clear glass, c d, with a brass disc at its centre, of such size as to 

 correctly represent the moon's apparent diameter as compared with that of the 

 sun. The edges of this disc are slightly serrated, to represent the moun- 

 tainous profile of the moon as shown in some of the eclipse pictures. In 

 front of this plate are arranged two doors opening on hinges, c K, and L i, 

 and having spiral springs also at these points, which tend to throw them open. 

 The door, hi, a little overlaps the other, and thus a bolt, m o n, engaging a 

 projection at H, secures both doors when they are shut. A circular orifice, 

 half in each door, corresponds with the solar disc on the rear glass. The 

 doors then being shut, and the plate c d drawn to the right, we see only the 

 bright solar disc with such sun spots and faculas as have been represented on 

 it. Then the plate c d being slowly pushed towards the left, we see the 

 moon's disc encroaching on the sun, and all the phenomena of the partial 

 phases, ending with " Baily's beads," which are of course due to the serrations 

 of the disc. An instant after, and as the disc entirely shuts off the sun, the 

 glass plate, c d, by pressing against the lug, w, of the bolt, shoots it, and 

 allows the doors to fly open, displaying the prominences and corona sur- 

 rounding the dark lunar disc. The figure represents the doors in the act of 

 flying open, and is correct in detail, except that the corona should appear 

 bright on a dark ground. Yet again, in illustration of the vivid brightness of 

 the crimson protuberances or hydrogen flames, as seen during a total eclipse, 

 the following device was employed : — A large coloured drawing of the moon, 

 surrounded by the solar corona, was stretched on an appropriate frame, and 

 the places of the prominences cut out. Behind these were attached a number 



