578 KANSAS CITY REVIEW OF SCIENCE, 
of the 41st Ohio Volunteers in November, 1861. His distinguished services 
caused his rapid promotion, being placed in charge of a brigade early in January, 
1862, and appointed Brigadier General of Volunteers in November, 1862. He 
was highly complimented for his ability and gallantry at Murfreesboro by General 
Rosecrans, and afterward, for similar services at Chicamauga and Chattanooga, 
by General Thomas. In April, 1865, he was commissioned Major General of 
Volunteers ‘‘for long and continued service of the highest character and for 
special acts of gallantry and service at Fort McAllister.” 
Since the war he has continued to serve his country as Colonel in the regular 
army, and has written several works as the results of his observations at home 
and abroad. After his return from Prussia, where he accompanied the army in 
the campaign against France and was present with it during its investment of 
Paris, he wrote ‘‘The School and the Army in Germany and France,” in which 
he gave the credit of the superiority cf the German soldiers to their thorough 
training in the public schools of their country. Later he published a report on 
the ‘‘Barren Lands of the Interior of the United States,’’ besides numerous 
magazine articles at different times. His confirmation was made by the unani- 
mous vote of the senate, and it is the universal verdict of the press, so far as we 
have seen, that the appointment was one of the best that could have been made 
from the regular army. 
A writer in a London paper, in discussing the photophone, says: The prob- 
lem which Prof. Bell has attacked is that of the transmission of speech, not by 
wires, electricity or any mechanical medium, but by the agency of light. The 
instrument which embodies the solution of this problem he has named the photo- 
phone. It bears the same relation to the telephone as the heliograph bears to the 
telegraph. You speak to a transmitting instrument which flashes the vibrations 
along a beam of light to a distant station, where a receiving instrument reconverts 
the light into audible speech. As in the case of that exquisite instrument, the 
telephone, so in the case of the photophone, the means to accomplish this end 
are of the most ridiculous simplicity. The transmitter consists of a plain silvered 
mirror of thin glass or mica. Against the back of this flexible mirror the speaker’s 
voice is directed. A powerful beam of light is caught from the sun and directed 
upon the mirror so as to be reflected straight to the distant station. This beam 
of light is caused by the speaker’s voice to be thrown into corresponding vibra- 
tions. At the distant station the beam is received by another mirror and con- 
centrated upon a simple disk of hard rubber, fixed as a diaphragm across the end 
of a hearing tube. ‘The intermittent rays throw the disk into vibration in a way 
not yet explained, yet with sufficient power to produce an audible result, thus 
reproducing the very tones of the speaker. Other receivers may be used, in 
which the variation in electrical resistance of selenium under varying illumination 
is the essential principle. Other substances beside hard rubber—gold, selenium, 
silver, iron, paper, and notably antimony—are similarly sensitive to light. 
