164 ROCHESTER ACADEiMY OF SCIENCE. 



With irons such a theory seems less plausible, while their 

 general similarity to terrestrial iron has led their cosmical charac- 

 ter to be more often doubted. Thus it is a matter of the greatest 

 satisfaction that a few irons have been seen to fall — their fall well 

 attested. These are 10 in number, the first being Hraschina 

 (Agram), Hungary, in 1751, and the last N'Goureyma in the 

 Sudan, Africa, in 1900. It is interesting to note that these 

 10 irons belong to no less than 5 out of the 23 groups of known 

 siderites, thus authenticating, as it were, nearly one-quarter 

 of all. These fall-seen siderites have ever been sought for 

 in collections. The same interest attaches itself to the 4 side- 

 rolites (Barea, Estherville, Marjalahti, and Veramin) which — out 

 of a total in the group of 29 — have been seen to fall. 



It is evident from the above that the factors of value in a large 

 meteorite collection are numerous and of very different degrees of 

 value; also, that they so link with and control each other that the 

 value of certain ones depends upon the value possessed by certain 

 others. Thus, for instance, if a collection is small — say of 200 or 

 250 kinds only — its size will become of less account as a factor of 

 excellence than would be the fact of its having a great propor- 

 tion of rare specimens, or of those showing leading points of 

 classification. In this case, too, the extent to which specimens have 

 been prepared for study (factor 9) will become of more account 

 than will factor 7 — the proportion of specimens of traditional or 

 historical value. 



The writer has had in mind in expression of relative values of 

 factors of excellence the consideration of a collection of the greatest 

 size. In this case the factor of number of kinds is given the leading 

 place (factor i) for the reason that it almost surely and of- neces- 

 sity includes all the other factors. And thus factor 2 — the average 

 weights and sizes of the individual specimens — becomes, as it other- 

 wisesurely would not, the second condition of value of the collection. 



It is evident that different persons will have different judgments 

 as to the relative points of value in the different factors which have 

 been given, according to their own views, and possibly according to 

 their success of management of their own collection. 



Further elucidation of this subject by others would be of great 

 interest and advantage to all who are interested in this restricted, 

 yet at the same time broad, subject. 



