HINTS AND HELPS. 163 



Dana's Revised " Manual of Mineralogy and Petrography " for ref- 

 erence purposes. It comprises 300 species and sub-species, in- 

 cludes most of the salient and many of the rare minerals described 

 in Dana's manual. It contains cubes, octahedrons, dodecahe- 

 drons, trapezohedrons, cleavages of rhombic and hexagonal 

 prisms, and crystallizations of the minerals which occur only, or 

 mainly, in crystallized form. Many of the specimens illustrate to 

 perfection the property of cleavage. In massive specimens, 

 numbers of the objects are duplicated, to show not only the con- 

 trasts in colors which the same mineral often possesses, but also 

 other differences between individuals of the same species taken 

 from different localities. The specimens are arranged in the 

 center of a square space, with the name of the species printed at 

 the bottom. The numbers on the left are consecutive, and those 

 on the right indicate the pages of the manual on which the 

 descriptions are given. The specimens are of good size, and are 

 quite characteristic of the species. The prices of this collection 

 are as follows : No. i, polished black walnut case ; edges and 

 corners rounded ; six drawers, which are secured by a hinged side, 

 in which is fitted a lock and key ; size 12 x6^ xy^, $30.00. No. 

 2, six pasteboard trays, with wooden sides ; contained in a strong 

 box, also of pasteboard ; size 12x6^x4 3^, $25. The collections 

 are furnished without the manual for $2.00 less. Should the col- 

 lection not be accepted by the purchaser, it may be returned, in 

 which event the remittance will be refunded, less cost of trans- 

 portation. Mr. Simmons will also furnish single specimens of 

 any size consistent with the nature and rarity of the minerals 

 wanted. His collections are indorsed by some of the highest 

 authorities in mineraiogical science. Circulars giving detailed 

 information will be mailed by him on application. 



A perfect understanding of zoology and mineralogy is best ob- 

 tained by the examination of representative specimens, correctly 

 named and located. James M. Southwick, Providence, R. I., 

 U. S. A., is very particular in the preparation and furnishing of 

 mineraiogical specimens, shells and eggs, also birds and mammals, 

 both mounted and in skins. He has also for sale all the tools re- 

 quired by zoological and botanical students. Circulars sent on 

 application. 



The study of microscopy is one in which an increasing number 

 of persons are yearly becoming interested. Societies for the 

 study of this delightful branch of science are springing up in all 

 parts of the country, and, like the Agassiz Association, their 

 necessity demands an organ which will give not only information 

 and instruction in this subject, but will also furnish society 



