

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 eartVs 

 shadow into the region of the sun's light 6 ? 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. 



Fig. 4 



Let S, be the sun's place, D the place 

 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 byieflected 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. 



