G. F. Barker—Spectroscopic Observation of the Solar Eclipse. 121 
Art. X1V.—On the Results of the Spectroscopic Observation of the 
Solar Eclipse of July 29th, 1878;* by GrorGE F. BARKER. 
To Professor Henry Draper, M.D., Director of the Draper Eclipse Expedition :— 
Dear Sir : I beg leave to submit to you herewith my Report 
on the spectroscopic observations made, and on the results 
obtained at Rawlins, Wyoming Territory, during the solar 
eclipse of July 29th, 1878, that portion of the work having 
been allotted to me by yourself in the organization of the 
expedition. : 
ison, and a Savart, a 
Senarmont, and an <Arago polariscope, for determining the 
rz spectroscope above men- 
giving it a lateral motion about a line pene through these 
centers, which constitutes an axis para [ 
observing telescope is similarly attached to the tube carrying 
the prism. These motions serve to alter the incidence of the 
rays upon the surface of the prism, and also to bring any 
* Read by permission of Dr. Draper at the St. Louis meeting of the American 
Association for the Advancement of Science. 
