REPORT OF ACTING ASSISTANT SECRETARY. 15 



auimals and plants and their development from the germ to the fully 

 adult individual, and special modifications of form and color by which 

 animals are protected from their enemies, the adaptations for peculiar 

 environments and modes of life, the characteristics 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. 



Third. — There should be developed a museum of practical geology in 

 the broadest sense, which will be of service to every producer and con- 

 sumer of American mineral products, and to all students of geology who 

 are engaged in either economic or purely scientific investigations. 



In addition to the series of rocks and fossils illustrating the stratig- 

 raphy and succession of the sedimentary rocks and the systematic col- 

 lection of minerals and ores, an exhibit showing how geologic work 

 benefits the daily life of the people should be developed. An illustra- 

 tion 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 geological 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 collection 

 of useful mineral products. This is desirable, but from a broad view of 

 illustrating the practical in addition to the scientific side of geology it 

 should be secondary. The best basis for classification on the practical 

 side of the museum exhibit aj^pears 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 shduld be arranged so 

 as to show the various kinds whose combination has resulted in the 

 final result as pig iron. In connection with this should be grouped the 

 geological phenomena, which should include representations of any 

 geological conditions connected with the original deposition and the 

 occurrence of iron ores. This might include the conditions which have 

 led to the oxidation of pyrite and other sulphur compounds of iron, and 

 to the development of hydrous oxides of iron ; also an illustration of what 

 has been demonstrated in regard to the solution of widely distributed 

 minerals in certain rocks and their subsequent concentration in ore 

 bodies by metasomatic action. All of the metals could be arranged 

 under such a classification, as also the nonmetallic products. To pre- 

 pare such an exhibit would require many years of work, the details of 

 which would be considered as each mineral product was taken in hand. 



