PRELIMINARY HANDBOOK OF THE DEPARTMENT OF GEOLOGY. 33 



According to the plan devised the exhibits of this section form two 

 independent series, which, as may readily be understood, are in part 

 duplicates of one another. These two series are (1) the geographic 

 series of ores and useful mineral substances and (2) the systematic series 

 of similar objects. Owing, however, to the present lack of proper room 

 and cases it has been fouud necessary to group the materials comprised 

 in this section under three heads, and inasmuch as they must so remain 

 until a new building is constructed or a balcony is placed around the 

 walls of the southwest court it will be best to so describe them here. 



These three series then arc : 



First. The collections of building and ornamental stones. 



Second. The geographic series of ores and other useful mineral sub- 

 stances. 



Third. The systematic series of ores and other useful mineral sub- 

 stances. 



I. — THE COLLECTION OF BUILDING AND ORNAMENTAL STONES. 



Under this head are included such stones as are of value in their 

 natural condition for structural or ornamental purposes. Artificial or 

 artifically colored materials are excluded. The nucleus of this collec- 

 tion was formed by the materials received from Philadelphia at the close 

 of the Centenuial Exposition in 1S76. By far the larger portion was, 

 however, collected during the investigations connected with the Tenth 

 Census in 1880, though mauy important additions have since been made 

 iu keeping pace with recent developments. This exhibit comprises 

 mainly materials from the United States, though foreign materials are 

 by no means excluded, and indeed particular efforts have been made 

 toward procuring such as are imported into the United States. 



The specimens of this collection are as a rule cut iu the form of 4-inch 

 cubes, the various faces of which are finished as follows : Polished in 

 front, drafted and pointed on the left side, drafted rock face on the 

 right side, rock face on the back, and smooth sanded on the top and 

 bottom. Stones not susceptible of a polish are merely smooth-sanded 

 on the front face. The collection is at present arranged by States in 

 fourteen floor upright and one wall case on the north side of the west 

 south range, while larger specimens occupy two large pyramids in the 

 southwest court and special bases wherever they can in our present 

 crowded condition be placed to the best advantage. 



This collection now comprises upwards of three thousand specimens 

 and has been described in detail in my work entitled "The collection 

 of building and ornamental stones in the U. S. National Museum: A 

 handbook and catalogue." 1 The following figures relative to the num- 

 ber of specimens may, however, be here given : 



1 Rep. Smith. Inst., 1885-'8<), Part n, pp. 277-648. 



