ZOOLOGY AND BOTANY^ MIOROSCOPYj ETC. 589 



carried out. These measurements, which were extended to the whole 

 spectrum, are scattered here and there in books, and moreover are not 

 all of equal value, being aflfected partly by personal and partly by 

 instrumental errors. For the purpose of forming a normal table for 

 the partial dispersions, I have collected about 200 of the best and 

 most authentic series of refractive indices, which embrace the Fraun- 

 hofer lines A, a, B, 0, D, E, b, F, G, Hi or at least the seven lines B, C, 

 D, E, F, G, Hi. From this series the accompanying table has been 

 compiled for optical purposes, in which the substances with the index 

 D or "D are arranged according to the total dispersions Hj — B or 

 "H - "B." 



[We have not thought it necessary to print the whole table of 173 

 data but have selected 44.] The observers were Fraunhofer (F.), 

 van der Willigen (v. W.), Baden-Powell (B. P.), Eudberg (R.), 

 Mascart (Ma.), Dutiron (Du.), Heusser (H.), Ditscheiner (D.), Stefan 

 (St.), Yerdet (V.), Yeress (Ve.), von Obermayr (v. 0.), Swan (Sw.), 

 Lohse (Lo.)." 



"The Genus Microscopista."*— The Annual Address for 1882 to 

 the Microscopical Society of Yictoria was delivered in November last 

 by the Yice-President, the Eev. J. J. Halley. 



After referring to the small number of members and the still 

 smaller number who contributed papers, the address continued as 

 follows : — " In such circumstances, perhaps, this Annual Address may 

 properly take the form of what would in theology be called apologetic. 

 We must defend our position, and show the raison d'etre of our exist- 

 ence. Looking, then, at our Society as we are accustomed to look at 

 the various divisions of sentient life as they come under our investi- 

 gation, we will proceed to examine the various species of what we 

 may call the genus Microscopista, the generic characteristics of which 

 are, that they examine minute objects with artificial aid more or less 

 elaborate and that they do this with a more or less useful end in 

 view. 



Of this great genus, whose habitat is the civilized world, the first 

 species is the M. delectata (sic), or the playing microscopist. This is 

 the lowest species in the scale of development, and some observers con- 

 sider that the other species are all derived from this one, while a few 

 who have no love for the genus afSrm that this is the one and only 

 species, the others so-called being only transient varieties. But 

 M. delectata, though often despised, is by no means to be set aside. 

 We will grant that in his hands the instrument is a plaything and 

 nothing more, — that he looks at the wondrous beauties revealed 

 merely to please the eye, — that he peers into quaint and curious forms 

 merely to satisfy curiosity, — that the valve of a diatom is interesting 

 to him merely as it is strange, and that the organs of an insect or the 

 home of a Bryozoon only allure as they are novel. In this there is 

 nothing to be despised. The great order of the Bimana must be 

 amused, and the more rational the amusement the better ; and surely 

 it is not less rational to find amusement in examining the wonders of 



* ' Southern Science Eecord,' ii. (1882) pp. 285-9. 



