138 Field Museum of Natural History — Reports, Vol. III. 



sustaining a weight of one ton. The top light in each case, which 

 is that intended to provide the chief area of display, is 44 by 68 

 inches in dimensions. Nine of these cases have been provided for 

 the hall. Considerable additions have been made to the clay collec- 

 tions, Hall 68, so that it has been necessary to add four cases to the 

 hall, and to consign to storage some of the material previously ex- 

 hibited there. The cases needed were obtained by moving some from 

 Hall 67. These additions necessitated an entire reinstallation, which 

 has been completed with very satisfactory results. The collection 

 now includes: Two synoptic cases, three cases of brick clays, two 

 cases of fire and potters' clays, and one case of china clays. So far 

 as possible, burned briquettes have been prepared of each clay ex- 

 hibited, so that the properties of the burned and raw product may 

 be seen together. In addition, a series of type briquettes has been 

 prepared, showing the effect on appearance, and other properties of 

 the clay, of different contents of lime, iron, etc. About five hundred 

 briquettes have been so prepared during the year for exhibition 

 with the collection. The series of diamond-bearing rocks of Arkan- 

 sas received from Mr. Millar has been installed in Hall 70. This 

 completes this collection quite satisfactorily, as the South African 

 and Brazilian series were already shown here. In Hall 71, the case 

 exteriors have been painted and some needed cleaning and reinstal- 

 lation performed. The collections in Hall 72 of ores of the precious 

 metals and lead have been rearranged so as to conform to a geograph- 

 ical classification, rather than one depending upon the metal in the ore, 

 as heretofore. This seemed desirable for several reasons, one being 

 that many districts have several metals combined in one ore, so that it 

 has been necessary, in order to represent the different metals fully, to 

 multiply the series more than was desirable. Again it has been found 

 that mining districts are better known, as a rule, than their ores, so that 

 ore is most easily looked for by the visitor under the name of the 

 district. Moreover, the relations of ores and ore deposits to each 

 other can generally be most clearly shown by an arrangement accord- 

 ing to districts. Accordingly the collections were rearranged, and the 

 following series are now shown in this hall: One case typical gold 

 ores and placer ores; one case ores from Alaska and British Columbia; 

 one case Washington ores; one case Oregon ores; one case ores 

 from California; three cases ores from Nevada; one case ores from 

 the Black Hills; one case ores from Utah; eleven cases ores from 

 Colorado; two cases of Arizona ores; three cases of New Mexico 



