On the Meteors of 13th November, 1833. 159 
took place, the cloud being smaller at first because the body was not 
fully on fire, and smaller at last because it had mostly burnt away. 
I feel constrained, therefore, contrary to my early impressions, to 
believe that the large meteors frequently descended to the region of 
the clouds. .Nor is it difficult to apprehend the reason why a body 
should fall so near to the earth and yet not reach it, since the density 
and of course the resistance of the air increases so rapidly as we 
approach the earth, and becomes so much more favorable to the 
combustion of an inflammable body. 
The short and fiery trains which followed the fire balls in their de- 
scent, are to be regarded as an ocular effect arising from the velocity 
of the body, the impression of the light remaining on the retina, as 
in the case of a whirled stick ignited at the end. 
‘In the previous part of this article, the query was raised, whether 
the trains were rendered luminous by being elevated above the earth’s 
shadow into the region of the sun’s light? On submitting this inquiry 
to an easy calculation, we are compelled to answer it in the negative, 
since the height required for such a purpose, even when the sun is 
only ten degrees below the horizon, is sixty one miles; and since 
trains were seen as early as three o’clock, or even earlier, the height 
necessary to bring the train within the sun’s light, becomes altogether 
too great to be admitted. This will be obvious from the subjoined 
calculation. | 
Let S, be the sun’s place, D the place Fig. 4. 
of the spectator, C the center of the 
earth, and AB the boundary of the 
earth’s shadow. Then a body above 
the point A will fall into the light of the 
sun, and may be seen by reflected light 
in the same manner as the moon and 
planets are. To find the height of A, 
that is AD, we have in the triangle 
ABC, right angled at B, the angle BCD, 
which is the depression of the sun below 
the horizon, and BC, the radius of the 
earth. Hence, cos. BCA : BC::rad.: © 
AC, then AC—CD=AD. 
Suppose the sun is fifty degrees below the horizon. Then the 
height of A would be two thousand two hundred and thirty seven 
miles. 
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