500 POPULAR SCIENCE MONTHLY. 



animals and plants and their development from the germ to tlie 

 fully adult individual, and special modifications of form and color 

 by which animals are protected from their enemies; the adapta- 

 tions for peculiar environments and modes of life; the characteris- 

 tics of youth, maturity, and old age; the variation in form, size, 

 and color among individuals of the same species; the domiciles and 

 other works constructed by birds, mammals, insects, and the like. 

 To these series should be added another of great importance, the 

 Economic Series, representing the animals and plants as related to 

 the activities and needs of man. Any one of these principal series 

 in its full development would more than fill the entire space now 

 available. 



3. There should be developed a museum of practical geology 

 in the broadest sense, which will be of service to every producer 

 and consumer of American mineral products, and to all students of 

 geology who are engaged in either economic or purely scientific in- 

 vestigations. 



In addition to the series of rocks and fossils illustrating the 

 stratigraphy and succession of the sedimentary rocks and the sys- 

 tematic collection of minerals and ores, an exhibit showing how geo- 

 logic work benefits the daily life of the people should be developed. 

 An illustration of this would be a representation of the artesian- 

 water supply of the semi-arid region, showing the stratification and 

 structure of the sedimentary rocks, and how hydrographic and geo- 

 logic investigations clearly indicate the regions in which artesian- 

 water development may be carried on successfully. Mining and 

 areal geology could also be illustrated in such manner as to place 

 before the student and intelligent observer the import and value 

 of such work. 



In most museums the principal effort has been to make a col- 

 lection of useful mineral products. This is desirable, but, from the 

 broad view of illustrating the practical in addition to the scientific 

 side of geology, it should be secondary. The best basis for classifi- 

 cation on the practical side of the museum exhibit appears to be 

 the finished mineral product. For instance, if pig iron be taken 

 as a key material in classification, the iron ores from which it has 

 been obtained should be arranged so as to show the various kinds 

 whose combination has resulted in the pig iron. In connection 

 with this should be grouped the geologic phenomena, which 

 should include any geologic conditions connected with the origi- 

 nal deposition and the occurrence of iron ores. This might in- 

 clude the conditions which have led to the oxidation of pyrite and 

 other sulpliur compounds of iron, and to the development of hydrous 

 oxides of iron; also an illustration of what has been demonstrated 



