Mat is, 1883.] 



SCIENCE. 



437 



talline forms of each important species have been 

 made out of plaster, and tlie surface hardened with 

 paraifine in order to give a smooth finish. These are 

 mounted in the same manner as the substances 

 whose structure tliey are used to illustrate. 



It was rightfully imagined, when the present gen- 

 eral plan of arrangement for the museum was adopted, 

 that the greatest obstacle in the path of any attempt 

 to show that there was a gradation in the natui-al 

 relations of the products of the earth would be the 

 department of mineralogy. It has been found, how- 

 ever, that the separation of minerals from the mother- 

 rocks, on account of their purer composition and defi- 

 nite forms, although purely artificial, has its logical 

 uses. It enables one to explain with directness and 

 precision the relations of all the elements and their 

 strictly inorgani'c compounds, and to prepare the 

 mind for the consideration of the more complicated 

 aspects of the geological and biological collections. 

 Mineralogy is therefore made the vehicle for the con- 

 veyance of almost all the preparatory facts in physics 

 and chemistry which are essential for the purpose of 

 the museum. 



While such definite marks of gradation cannot be 

 found in minerals as among animals and plants, 

 there is in nearly every division of minerals, even 

 "with their present entirely artificial and probably 

 unnatural classification, such distinctions as those of 

 anhydrous and hydrou.s groups, the simple and double 

 sulphides, the binary and ternary compounds. These 

 have not yet been brought into correlation with the 

 molecular structure, or with each other, in any natu- 

 ral classification ; and therefore we cannot say that 

 the hydrous compounds are necessarily, on account 

 of the addition of water to their chemical composi- 

 tion, more complicated in their molecular structure 

 than the anhydrous, or that the same is true of the 

 double as compared with the simple sulphides, or yet 

 of the ternary as compared with the binary com- 

 pounds. 



Notwithstanding these difiiculties, the facts are in 

 every case facts of gradation. It makes no difference 

 whether the gradation leads up or down, or mingles 

 both of these tendencies. Whatever direction the 

 true classification may eventually take is immaterial. 

 The indications of what is already known show that 

 gradation of some sort must be its marked character- 

 istic; and this alone is sufficient to harmonize the 

 whole provisionally with the other departments of 

 the museum. 



Important support, however, is derived from an 

 opinion in which all chemists and mineralogists con- 

 sulted seem disposed to agree. There are decided 

 grounds for the belief that both the chemical and the 

 molecular constitution of the elements may be con- 

 sidered as less complicated than that of the purely 

 inorganic and probably derivative compounds, and 

 these, in turn, simpler than the hydro-carbons. The- 

 oretically, also, one is safe in assuming that the latter, 

 which are the products of organic bodies comjjosed 

 of their fossil remains, oils, gums, etc., more or less 

 altered by the physical and chemical conditions to 

 which they have been subjected, are of later deriva- 

 tion in time than the strictly inorganic compounds, 

 and that these, in turn, are probably more recent, as 

 a rule, than the elements of which they are made 

 up. 



These fundamental facts are quite sufficient for the 

 purjioses of the collection, and permit a demonstra- 

 tion of the fact that the same principles of classifica- 

 tion apply in this department as in all others, 

 whether inorganic or organic. 



The curator is already in receipt of letters from 

 eminent teachers and others, expressing their gratifi- 

 cation at the results of the work in this department, 

 and some of them strongly urge the immediate publi- 

 cation of a proper catalogue. 



Harvard university, Cambridge, Mass, 



The Jefferson physical laboratory. — The plans of 

 the new physical laboratory, presented to the univer- 

 sity by Mr. T. Jefferson Coolidge, have now been so 

 far discussed that we may give a general account of 

 them. The building will be placed about in the cen- 

 tre of Holmes Field, in the rear of the Scientific 

 school, to avoid as much as possible all jars from 

 passing vehicles. The nearest street (Oxford Street) 

 will be about 300 feet from the east wing. 



The building consists of an eastern and a western 

 section, each 60 X 60, connected by a central piece 

 SO X 40 ft. The eastern section will contain a large 

 lecture-room, with a seating-capacity of between 275 

 and 300 students; above this, an immense laboratory, 

 60 X 60 ft., for the general use of undergraduates and 

 less advanced students. The basement of this sec- 

 tion will be occupied by a workshop, a battery-room, 

 boilers, and coal-bins. The north side of tlje east 

 section, flanking the lecture-room, is occupied by 

 three stories of rooms for the physical cabinet. These 

 also extend on the north side of tlie central piece, 

 and are so arranged as to lead conveniently into the 

 lecture-room, the general laboratory, the recitation- 

 rooms, and also into the western section, where the 

 rooms for special investigations are located. 



In the central piece, besides the space occupied by 

 the cabinet, there are two recitation-rooms, a balance- 

 room on the first floor, and, on the third floor, rooms 

 for electric measurements, photometry, and a general 

 library and balance room. Small entries and stair- 

 ways at tlie east and west end of the centre piece 

 give easy access to all parts of the building for the 

 professors and special students. The undergraduates 

 have access to the lecture-room and general labora- 

 tory at the east end of the building by a stairway re-' 

 moved as far as practicable from the rooms devoted 

 to special investigations. This arrangement, and the 

 position of the engines and dynamos on the outside 

 of the building across a deep insulating ditch, will 

 prevent the jar of the machinery and the tramping 

 of students from interfering with delicate observa- 

 tions. 



The basement of tlie central piece is occupied by 

 receiving-rooms, and storage for heavy pieces of ap- 

 paratus. 



The western section is the one which the professors 

 and instructors of physics have most carefully con- 

 sidered. The lower floor contains rooms of moderate 

 size, devoted to general use and special investigations, 

 — rooms which will be fitted up with reference to 

 electricity, heat, magnetism, and sound. In each 

 room of the first floor there are independent jjiers, 

 built up from the basement, insulated from the walls 

 and floors upon which delicate instruments are to be 

 placed. Similar rooms devoted to optics, electricity, 

 and the Eumford laboratory, are located upon the 

 second story. The third floor is as yet assigned to 

 no definite use, and, with the exception of a room for 

 photography, can be left to meet the wants of the 

 future. The basement of this section is occupied by 

 a room for magnetism, one for heat, and one for 

 weights and measures. A room for constant temper- 

 ature is excavated below the basement floor in the 

 centre of the building. 



To afford facilities for the study of atmospheric 

 physics and experiments for which great height is 



