394 Scientific Intelligence. 
The method we have here described we can most confidently 
recommend as a most efficient and accurate means of determining 
J. C. P., JR. 
11. The Influence of the density of a body upon its ‘Light- 
ries - 
bing power.—Professor Guan has conducted a se ot ex 
any change of absorption with change of density that it must be 
very small. He is inclined to think that his results give evidence 
varies greatly 
85° the effects are very faint; between 75° and 60° they are com- 
t 
the analyzer from extinction, and so forward. 
subject to exceptions.— Phil. Mag., March, 1878, p. 161 
he Velocit i 
A. Micuetson, Ensign U. S. Navy, Instructor in Physics and 
sak 
any distance. the figure, S is a division ore scale ruled on 
ed M, a revolving plane mirror; L, an achromatic lens; 8", 2 
xed plane mirror, at any distance from : 
The point S is so situated that its image §’ reflected in the mir 
