On the Meteors of ISth November •, 1833. 



155 



6. Some of the larger meteors must have been bodies of great size. 



According to the testimony of various individuals, in different parts 

 of the United States, a few fire balls appeared as large as the full 

 moon. Thus Dr. Smith observes (p. 379) : " By far the most mag- 

 nificent meteor crossed the vertical meridian about 3 o'clock A. M. 

 Its course was nearly due west, in length by conjecture about 45°, 

 and at a distance of about 25° south of the zenith, In size, it ap- 

 peared somewhat larger than the full moon rising. I was startled 

 by the splendid light in which the surrounding scene was exhibited, 

 rendering even small objects quite visible ; but I heard no noise, al- 

 though every sense seemed to be suddenly aroused, if I may so speak, 

 in sympathy with the violent impression on the sight."* 



This description implies not only that the body was apparently 

 very large, but that it was at a considerable distance from the specta- 

 tor. Now a body in order to appear as large as the moon, will have 

 the respective diameters, calculated for different distances, assigned 

 in the following table. 



Miles Distant 



no 



55 

 22 

 11 



i 



Miles in Diameter. 



t 



if 

 4 



1 



5 



■J 



1 



I 



2 



_1 

 1 1 



That is, a body appearing as large as the moon at the distance of 

 110 miles, must be one mile in diameter ; at the distance of 22 miles, 

 one fifth of a mile, or 1056 feet ; and even, if only at the distance of 

 a mile, it must be 48 feet in diameter. It may be impossible to de- 

 cide at which of these distances the meteor seen by Dr. Smith, ought 

 to be taken ; but the position with regard to the spectator, the ap- 

 parent distance, and continued brilliancy indicate, that its real dis- 

 tance was considerable. 



Let us, (for a very moderate estimate,) suppose it to have been 

 eleven miles off, and appearing as large as the full moon j it must 

 then have had a diameter of 528 feet. But if any one should choose 



* Humboldt says some of the fire balls of 1799 were from 1° to 1° 15' in diame- 

 ter, and consequently more than twice as large as the moon. (Pers. ^Narrative III. 

 332.) 



t 240.000 : 110 : : 2180 : 1 nearly. 



