62 APPENDIX TO THE REPORT OF THE SECRETARY. 



made an arraugement with Mr. Thomas Donaldson, one of the Centen- 

 nial commissioners of Idaho, to visit the principal mining regions west 

 of the Kocky Mountains, at its expense, for the purpose of collecting 

 illustrations of the resources of the country in gold, silver, and mercury. 

 Fortified by letters of credit from the commission, Mr. Donaldson pro- 

 ceeded on his mission, and was enabled to secure many valuable collec- 

 tions at little or no cost ; the proprietors of mines especially manifest- 

 ing a desire to be appropriately represented in the Exhibition and pre- 

 senting many specimens not only interesting in a scientific point of view, 

 but of much intrinsic value. 



*^ A concession, at the same time, was obtained by Mr. Donaldson from 

 the railroad companies between Philadelphia and San Francisco by 

 which they agreed to transport a given number of tons of these minerals 

 free of charge, and thus greatly to reduce the cost of the enterprise. 

 '^ After the organization of the Government board on Executive Depart- 

 ments, the Board of Finance came to the conclusion that it was not expe- 

 dient for the Centennial Commission to undertake a separate display of 

 minerals, and an arrangement was, therefore, made to turn over the 

 collections made by Mr. Donaldson to the Smithsonian Institution on 

 payment of the expenses incurred and its agreement to continue the en- 

 gagement with Mr. Donaldson to the end of the year 1875. This was 

 done to the satisfaction of all parties, so that since the 8th of May Mr. 

 Donaldson has been in the employ of the Institution, and the collections 

 made by him are in Philadelphia or on the way thither. " 



The State geologists of a number of the States have also co-operated in 

 the efforts toward a mineral exhibition, and also a large number of pro- 

 prietors of mining establishments and others who had it in their power 

 to render any aid. 



The present prospect in regard to the mineral display is entirely sat- 

 isfactory. It is believed that no important interest in this direction will 

 be unrepresented, and that the general exhibition, to consist of ores and 

 their metals, with their slags and by-products, the crude and refined 

 metals, the building-stones, the clays, the marbles, the coals, slates, &c., 

 will be quite a perfect picture of the industries as at present developed 

 throughout the United States. There will be also a series of the simple 

 applications of the different substances, such as the petroleum products, 

 the coal-tar products, specimens of terra-cotta, pottery, and porcelain as 

 illustrating the clays, some manufactured articles of the metals, pol- 

 ished slabs of the marbles, &c. 



Care has been taken to obtain the various specimens in sufficient size 

 to make an imposing feature j the metals and coals, as far as possible, 

 having been selected in cubes of two feet each way ; the building-stones 

 are in cubes of twelve and six inches, the latter size having been adopted 

 for most of the ores also. 



It is proposed to exhibit on the large Smithsonian map the geological 

 features of the country, as also the general distribution of the valuable 



