264 LAMPLAND— ECLIPSE OBSERVATIONS 



has yet been given in the previous attempts to decide the matter. It 

 was hoped that it might have been possible to include some satis- 

 factory observations in this communication. The preliminary work 

 done thus far does not warrant a stronger statement than to say 

 that further comparisons should be made, at least in the case of 

 one of the series of prominent arches. Unfortunately the material 

 at present available is not wholly satisfactory for such difficult 

 comparisons. As prominence detail is frequently subject to rapid 

 change it does not seem worth while to add anything further than 

 already given relative to such comparisons. The marked changes 

 that occurred in the great eruptive prominence are obvious upon 

 casual inspection. 



Our appreciative thanks are due to Dr. Campbell for generously 

 granting permission to make use of three very fine positives from 

 plates of short exposure taken at Goldendale, sent us recently. 



Dr. Slipher gives herewith a summary of his observations of the 

 spectrum : 



Spectrum Observations of the Corona. 



The spectrograms recorded a strictly continuous spectrum for 

 the inner corona crossed by the three coronal emissions of wave- 

 lengths 4086, 4231 and 5303.0; and a faint solar dark-line spectrum 

 for the outer corona which seems to be of true coronal origin. The 

 objective prism plates registered the continuous spectrum of certain 

 prominences in addition to their usual emissions, and the green 

 coronium ring between the fragmentary ones of hydrogen F and 

 helium D3. The distribution of the intensity of the green ring 

 implies that the substance " coronium " is generally abundant along 

 those parts of the sun's limb occupied by prominences and from 

 which flow the great extensions of the corona, and that it is sparse 

 along those sections of the limb occupied by the bristling streamers 

 typical of the polar regions. 



The observational results given in the present paper are the joint 



work of Dr. V. M. Slipher, Mr. E. C. Slipher and the writer. A 



general account of the organization and work of the expedition has 



been published in one of the astronomical journals. 



Lowell Observatory, 

 Flagstaff, Arizona. 



