278 MILLER— SPROUL OBSERVATORY ECLIPSE EXPEDITION. 



I was able to show that if these streamers were thus mechanically 

 produced that there would result in each corona a few streamers of 

 such a shape that one could draw a radius vector from the center of 

 the sun which would be tangent to the streamer and that one could 

 find for streamers of this shape the following things :^ the point on 

 the sun from which the streamer issued, the velocity with which the 

 particles in it were ejected, the velocity of the particles at any time, 

 the paths described by the particles and if we assume the law of the 

 repulsive force, we can find its magnitude. Theoretically, there 

 should be very few streamers of this shape. In an examination of 

 the Lick plates made at six eclipses between 1893 and 1908, I found 

 sixteen streamers of this type ; and on the plate made by Father 

 Cortie at a time of minimum sun-spots in 1914, Aliss Caroline Smed- 

 ley, an assistant at the Sproul Observatory, found and measured two 

 streamers of this type, and in the corona of 1918 there is unmis- 

 takably one and probably two streamers of this form. These also 

 Miss Smedley measured and reduced. There always exists the pos- 

 sibility that the form of the streamer has been affected by local 

 causes and the arches which I have just discussed makes it ap- 

 parent that at least near the surface of the sun at this eclipse local 

 forces were very effective, but the streamers that we found in this 

 corona and which we measured stand out separated from these dis- 

 turbed regions and away from the prominences. 



This theory works admirably with one exception which I shall 

 now discuss. Since the solution gives the form of the paths in 

 which the particles in the streamer are traveling, one should be able 

 to compute an ephemeris for each particle and using the constants 

 determined in the solution compute a streamer that exactly repro- 

 duces the streamer from which the constants were found. It turns 

 out that with these constants the streamer on the sunward side of 

 the tangential point P and for some distance on the other side of 

 the P the streamer can be perfectly represented, but that when we 

 compute the position of the particles at a distance of two or tiiree 

 radii from the sun, that the streamer thus plotted turns back nnich 

 more abruptly than those do that are shown in the ]:)hotograph. \\'e 

 have ])lotted with the constants obtained by the solution several 



- See Fig. 4, loc. cit. 



