REPORT OF ASSISTANT SECRETARV. 23 



Ainon,u' the more importaut accessions luivc been several relief maps 

 received from the Geological Survey, a collection of rocks and building 

 stones from IMexico, a series of the rocks of Continental Europe, and a 

 series of tyi)ical marbles and building stones from South Carolina, etc^ 



There are several groups of exhibition specimens in process of prepara- 

 tion, among them being a strnctural series, a lithological series, and a 

 series of building and ornamental stones. These are in part on exhibi- 

 tion, though not iu their proper places in the systematic collection. 



The curator, Mr. Merrill, is engaged in investigations upon the min- 

 eralogy of the District of Columbia, the origin and nature of fulgurites. 

 and the darabilit3' of building stones, besides carrying on studies on 

 local petrography; and has just completed a catalogue of the collection 

 of building stones now iu the Museum. 



The total number of specimens iu the collection is estimated at 

 20,047, of which 17,047 belong to the reserve series. Of the latter num- 

 ber 5,313 are on exhibition, 2,730 being specimens of building and orna- 

 Biental stones, and 1,820 belonging to the educational series of rocks 

 and rock-forming minerals. There are, also, in the collection 3,400 

 thin sections of rocks prepared for microscopic study. Of these nearly 

 200 have been added during the year. 



DEl'AHTMKXT OF :\IETALLURGY ANH ECONOMIC GEOLOGY. 



Owing to the fact that so great a mass of material is already assignod 

 this department, which is under the curatorship of Mr. F. P. Dewey, it 

 has not been considered wise to solicit additional collections, although 

 much has been received during the year. 



The special attention of the curator has been given to the arrange- 

 ment and classification of the mass of material received from the Insti- 

 tute of ]\Iining Engineers, i)art of which arrived during this year. 



The preparation of the exhibition series has been going steadily for- 

 ward, and a portion has been i)laced on exhibition as a preliminary dis- 

 play. The curator has commenced the preparation of a descri[)tive cata- 

 logue of the systematic collections, to serve as a guide to visitors. 



For tlirt!»e years past the curator has been employed in an investiga- 

 tion of the physical properties of coke, and has j)ublished a paper upon 

 the porosity and specific gravity of different kinds of this material. 



Tiie total luimber of si)ecimens in the collection is estimated at 48,000, 

 of which 17,000 are on exhibition. During the year 5,500 entries were 

 made, iucbadiug 8,552 specimens. 



