NO. 1 6 METEOR-ORBITS IX THE SOLAR SYSTEM — VON NIESSL 25 



For the star shower of the Leonids in November, Newton ' com- 

 puted from 78 determinations the average altitudes of luminosity 

 155 km. and extinction 98 km. According to this the whole path of 

 light for the November Leonids was higher than for the August 

 Perseids which is evidently in connection with the fact that the 

 Leonids entered into the atmosphere with a relative velocity of about 

 70 km. and the Perseids with only 60 km. Moreover the masses of 

 the November stream seem also to have special chemical characters.^ 



The determination of 159 altitudes of shooting-stars from the 

 fifth to the first magnitude, and af the most varied radiants,^ there- 

 fore also including some very slight velocities, gives in general for the 

 luminosity 108.5 km. and for the extinction 86.3 km. which is there- 

 fore only a slight variation from the values found for the August 

 Perseids. 



For the large meteors, including those with detonations and those 

 with falling meteorites, and from determinations that are especially 

 reliable, but without selection of the greatest phenomena, I found for 

 the luminosity from 121 cases an altitude of 138.6 km. 



For the extinction from 213 cases an altitude of 49.7 km. 



This collection of data shows the influence of the larger masses, 

 especially because of the comparatively slight altitude of the stopping 

 point and therefore because of the deeper penetration into the atmos- 

 phere. This is shown still more plainly by a further classification. 

 For the altitude of the stopping point I found* on the average 

 60 km. for 147 fire balls without detonations; 31 km. for 57 meteors 

 with detonations; 22 km. for 16 falls of meteorites, thus it may 

 well be proper to explain these different types of shooting-stars as 

 due to a gradual increase in mass, since larger masses experience a 

 relatively smaller resistance in the atmosphere and thus can penetrate 

 deeper than the smaller masses. 



Still more important are the relations of the altitude of the terminal 

 point to the value of the geocentric velocities that we obtain from 

 the observations. In order to avoid as far as possible any one-sided 



* H. A. Newton, ibid. 



*The Leonids among all meteors provide the longest enduring luminous 

 tails in the atmosphere. 



* Memoirs of the British Astronomical Association, Vols. 9, 12. Part i 

 (1900-1903). 



■*G. V. Niessl, " Uber die Periheldistanzen und andere Bahnelemente jener 

 Meteoriten, deren Fallerscheinungen mit einiger Sicherheit beobachtet werden 

 konnten," Briinn (1891). 



