38 SMITHSONIAN MISCIiLLANKOlJS COLLECTIONS VOL. 66 



Apart from the details that are uniniportaut in the estahhshment 

 of this point, hoth these series show the expected connection between 

 the elonf^ation and (he terminal altitude. In the first list the fact that 

 the latter terminal altitudes are in }.:;eneral j.»reater than in the second 

 list is certainly because the meteors in the former list are principally 

 the smaller kind thai burn up at great altitudes, whereas mine or the 

 second list relates mostly to the laKjje meteors. In this respect, there- 

 fore, the latter is to a certain extent a supplementary continuation of 

 the first. In part, also, the smaller oliserved velocity of the deep- 

 penetratin}^- meteors must be the result of the diminution of the 

 velocity during the path through the atmosphere. The final stoppage 

 of the meteor is almost instantaneous, still there are certain phe- 

 nomena that result from observations that relate only to the lowest 

 portion of the path in the deeper layers of the atmosphere that show 

 slighter velocities than the average velocity that results from a con- 

 sideration of the whole path of the meteor in the same case.* But of 

 course the error in the estimation oi short intervals of time renders 

 difficult any decision on this point. 



( OMl'AHISON WITH THE THEOUV OF THE KESLSTANi E OK THE 

 ATMOSPHEUE 



In order to compute the resistance of the air experienced by the 

 meteor in its individual phases, one has atlempled lo utilize the expe- 

 riences which have been deduced from experiments with the spherical 

 balls of artillery. The following collection and sununary is based 

 ujion the formula for resistance given by Kobfrl." It assumes a 

 vertical movement of a spherical body weighing ii8 grams having a 

 density of 3.5 and a radius of 2 cm. The two assumed velocities 

 with which the l)all enters the atmosphere relate to the extreme values 

 of a paraliolic orbit, viz.; at the apex and the anti-apex. If for the 

 same density we have another radius of the sphere, viz. : 2r cm., and 

 if the inclination of the path toward the horizon be li, then in the 

 column for the velocity the values will remain unchanged if lli<' 

 corresjjonding atmospheric pressure be multiplied by /' sin //. 



T/. G. V. Niessl, Weill, tier., 114 (1905), !»• ISH. 



' Schiaparelli, pp. 2j and 34 after S. licibert, "Del nioln dti prtijrilili iit-i 

 mezzi resiatenti." Torino, 1855. (Memorie dell' Acadeniiu delle scienze di 

 Torino, II, 9, 16.) 



