290 On Luminosity of Meteors from Solar Reflexion. 
as far as we know, far too great to admit of our seeing ordinary 
shooting-stars, at least in countries within the tropics, and if 
shining by reflected solar light. 
Fig. 2. 
*m 
The distance to the outside of the umbra in latitude 45° half- 
way between w and 7, as at w/, would certainly be considerably 
less than 5547 miles; though this would not vitally affect the 
question, as the distance towards c’ would proportionately in- 
crease ; and w' a would still be over 1500 miles at midnight. 
If the altitude of the meteor be, say 64°, dz being= 0 
=8895 miles, then wd=8900 miles; and if scen in the zenith 
at O, its distance would not be less than 871,710 miles, as seen 
from w, the supposed centre of the cone of shadow. 
Now as the average distance of shooting-stars at the time of 
their visibility is not much more than 100 miles, varying from 
50 to 150 miles, and as we usually see them in all quarters of 
the heavens at an average elevation of at least 45 degrees, it is 
pretty clear, I think, if the preceding calculations and supposi- 
tions are correct, that the majority of the shooting-stars we see 
do not shine by reflected solar light. 
I may at a future time offer some observations on other and 
more probable causes of luminosity in meteors and shooting-stars, 
and in the mean time refer those interested in this subject to the 
last Report of the British Association for Leeds in 1858, by 
the Rev. Baden Powell. The theory of Mr. Daniel Vaughan, 
alluded to in that Report, deserves attention. 
