M. C. Ihiseng— Velocity of Sound in Wood. 125 
Fraunhofer lines in the coronal spectrum shows conclusively 
the presence of reflected sunlight in the light of the corona and 
goes to establish the theory, long ago suggested, that masses of 
ae amie 
the fact of the increased brightness of the continuous spectrum, 
as compared with the intensity of the dark lines of Fraunhofer, 
goes to strengthen the probability that there is still other light 
im the corona which comes to us from the incandescent liquid 
or solid matter of these intensely heated meteoric masses 
These conclusions, deduced very simply from my own spectro- 
scopic results, agree completely, I am happy to find, wit 
those drawn from your most excellent photographs, as well as 
froin the ingenious heat-measurements of Dr. Edison and the 
polariscopie determinations of Dr. Morton. 
In concluding this Report, you will permit me I am sure, to 
express the great gratification which the Draper Eclipse Ex- 
pedition has continually afforded me. The delight at being 
able to witness a total eclipse of the sun, has been intensified 
by the complete success of all the attempts made to observe it, 
and by the most agreeable companionship during the trip. My 
obligation to you for the opportunity is as profound as my 
thanks to you for it are sincere and cordial. 
Truly yours, GeorGE F. BARKER. 
Philadelphia, August 10th, 1878. 
\ 
ArT. XV.—On a mode of measuring the Velocity of Sound in 
Wood ; by Maanus C. Intsene, Ph.D. 
[Read before the National Academy of Science, October, 1877.] 
THE subject of this paper was suggested to me by Professor 
Rood, and the work carried out under his direction in the 
glass plate, and thus to register vibrations ; he did not carry 
the project into effect, Wertheim+ in his excellent work em- 
* Journal de Ecole Polytechnic Cohier, xxiii, 19. 
+ ce alen, Erginz., ii, 1. 
Am. Jour. Sci.—Tuirp Serres, VoL. XVII, No. 98.—Frs., 1879. 
9 
