Jan., 1922. Annual Report of the Director. 33 



cases contains a synoptic collection which illustrates the group and 

 serves as a key to the larger collection. The nature, origin and general 

 character of the clays of each group are shown by labels and the 

 relations of the groups to each other are indicated by diagrams 

 painted on the floors of the cases, the lines of which connect with 

 each specimen in such a manner as to make its relations to the other 

 specimens evident. Numerous specimens of each group of clays are 

 shown in eight adjoining cases. A briquette burned from the same 

 clay as the specimen is frequently installed with the specimen in order 

 to show the character of the material in its most used form. While 

 the number of clay deposits is so great that anything like a complete 

 collection is both impossible and undesirable, enough members of 

 each group are shown to illustrate the great variety in character 

 which different deposits of this useful substance assume. A collec- 

 tion illustrating the different effects obtained by variations in the 

 methods of burning clay, which was received during the year, has 

 also been installed here. Several groups of specimens also illustrate 

 the effect of various impurities and minor components of clay upon 

 its character when burned, while the use of clay in pottery is illustrated 

 by a series showing stages in the manufacture of Japanese pottery. 

 Other cases in the hall contain collections of other earthy substances 

 of economic interest. Thus a collection of natural and Portland 

 cements fills half of one case and a collection of fuller's earths the 

 other half. Another case contains a collection of various kinds of 

 sands of industrial importance, such as molding and glass sands. 

 Uses of silica in its various forms are illustrated synoptically in 

 another case. Earthy pigments, including ochers and allied paint 

 substances, occupy an upright case. Two square, upright cases contain 

 large specimens of iron ore and fluorite and a large model of the 

 Chandler iron mine has been installed at the west end of the hall. 

 This model, before installation, was thoroughly renovated, missing 

 timbering restored, a new head frame built and the whole model 

 repainted. The installation of Skiff Hall had been practically com- 

 pleted in 1920, but a few remaining details, such as the installation 

 of miscellaneous labels and readjustment of the fastenings of the 

 cases were accomplished during the past year. Some specimens 

 received during the year were also installed among their respective 

 groups. A mahogany pedestal was prepared for the bust of Dr. 

 Skiff presented by Mrs. Skiff, and the bust, on this pedestal, was 

 installed in the center of the hall. Installation of Higinbotham Hall 

 was delayed about a month beyond that of the rest of the Museum, 

 but owing to the isolated position of this hall, no inconvenience 



