26 H. A. LENEHAN. 
Under the exceptionally fine conditions it was possible to 
see that the form of the zodiacal light was a spherical 
triangle, with its apex near the ecliptic. At the time of 
observation (3h. 40m. Paris mean time) the height of the 
apex was 92 degrees; the length of the light, reckoning 
from the centre of the sun, 80 degrees, and its width at 
the horizon 25 degrees. The intensity increased towards 
the centre, but its maximum was not situated on the 
ecliptic, being about 3 degrees from it. Three zones 
were distinguishable in the body of the light, that 
described above, and of general feeble luminosity; a 
medial portion slightly parabolic in outline, and a central 
luminosity in the form of a parabola. As an approximate 
measure of intensity, the light at 55 degrees from the sun 
was estimated to be equal to that of the Milky Way, 
at 40 degrees about double this, and at 30 degrees three 
times. The colour was very difficult to define on account 
of the faintness of the light, but it was thought to be 
white with a trace of green. The paper concludes with 
various suggestions concerning the probable cause of the 
phenomenon. 
Reflecting Powers of Glass and Silvered Glass Mirrors.— 
Mr. C. A. Chant in a paper read before the Royal 
Astronomical Society of Canada, presents a review of 
former investigations on the reflecting power of various 
substances. For perpendicular incidence on numerous 
metals and alloys for wave-lengths ranging from 250 
to 1500 mm., the general conclusion is that the reflectivity 
increases with the wave-length. Work on glass mirrors 
shows that the reflection will gradually fall off with age, 
although there may be no perceptible tarnish on the 
polished surface. A special arrangement was a photo- 
metric optical bench to admit of the mirror under 
comparison and its illuminant (a Hefner lamp) to be 
