126 Meteoric shower of November, 1872, in Italy. 
before the resonator, taken as unity, gives the reflecting power 
of the substance plus its absorbing power. 
It is very important, in such measures, to be sure that a plane 
wave surface is reflected from the mirror. This character io 
wave can be approximately obtained by placing the mouth 0 
a closed organ-pipe at or very near the principle focus of the 
mirror and testing, by the method we have described above, 
the equality of intensity of the vibrating air in front of the 
mirror as we recede along its axis. We thus, by trial, at last 
succeed in obtaining a sufficiently plane wave-surface. are 
must also be taken that the surface of the reflecting substance 18 
so large that no inflected vibrations can act on the resonator. | 
ave made several measures of intensity and of rT 
ting and reflecting powers, but as the experiments were made 
in a room whose walls, ceiling and floor gave reflected sonorous 
waves, I will not present measures until I have arranged suit- 
able apartments for their accurate execution. 
November 13th, 1872. 
Art. XVIL—Meteoric Shower of November 27-28, 1872, as 0b- 
served at the Observatory of Moncalieri (Italy); by rae 
Denza. (From a letter addressed to Admiral Sanps, U. » 
Naval Observatory, Washington, D. C.)* 
A GREAT meteoric shower, the greatest hitherto observed in 
our country, was seen yesterday evening at this Observatory: 
and I am sure that it must have been observed likewise 12 
* Translated under the direction of Admiral Sands, Superintendent of the Ob- 
servatory, and by him communicated to this Journal. 
