NO. 1 6 METEOR-ORBITS IN THE SOLAR SYSTEM VON NIESSL 23 



of errors of observation. These characteristics belong only to the 

 transverse departures from the corrected apparent path. 



These departures deduced from 217 cases for the initial point 

 average ±4.2. They are deduced for the initial point in a similar 

 way as for the terminal point, but by excluding rough data more 

 frequently than in the latter case. 



The apparent relations to the stars when they are determined im- 

 mediately after the observations resulted in giving the average error 

 of such a relation as ±3.5 degrees for the initial or the terminal point 

 respectively. 



C. ESTIMATES OF THE APPARENT INCLINATIONS OF THE OBSERVED PATH 



These estimates show from an average of 250 cases a mean error 

 of ±6.5 degrees. Such estimates generally refer to the vertical 

 through the observed terminal point, or some other specific point in 

 the path and were generally obtained by graphic sketches. Radiants 

 that do not lie far above the horizon were generally affected by only 

 a small part of this uncertainty. 



D. THE ACCURACY ATTAINED IN THE DETERMINATION OF THE RADIANTS 



Of large and generally detonating meteorites, 43 reliable determina- 

 tions for 537 apparent paths, therefore on the average 12 or 13 obser- 

 vations for each case, gave the average error in the location of these 

 points on the sky at ±3.3 degrees. 



The number of the orbital paths in the individual cases was very 

 uneven, exceeding 40 in many cases, but was often only three or four. 



At the present time more than 420 radiants of detonating meteors 

 have been found, of which, however, about 30 per cent are identical 

 with others. Much larger is the number of the radiants of shooting- 

 stars listed in the last catalog. Denning ^ compiled from the appro- 

 priate literature as well as from his own observations 4,367 ^ such 

 radiant points of which, however, probably more than half coincide 

 with others. 



When he remarks' that on the average, during every night, more 

 than 50 radiants are in action, this is quite correct, but on account of 

 the lesser frequency of individual meteors, many of these radiants 

 cannot be demonstrated every night at the same place and during the 

 same year. , 



^ W. F. Denning, General Catalogue (1899). 



' Large numbers of these radiants have no proved existence and are prob- 

 ably fictitious. C. P. Olivier. 

 ' W. F. Denning, ibid., p. 203. 



