30 EEPOET OF THE SECEETAEY. 



extended series of experiments, however, has been that which relates 

 to the condition of the air, and the mode of ventilation of the United 

 States Capitol. This subject was referred by Mr. Thomas U. Walter, 

 the architect of the Capitol, to the Secretary of this Institution. 

 The plan of the investigation having been determined, the experi- 

 ments have principally been made by Br, Wetherill. The result of 

 this investigation, it is believed, will not only throw additional light 

 on the points for which it was instituted, but also form an interesting 

 addition to the subject of ventilation. The work in the laboratory, 

 also by Dr. Wetherill, comprised various researches upon subjects of 

 chemical science. Of these, three, viz. : "On the nature of the so- 

 called ammonium amalgam ;" "On the crystallization of sulphur ; ' ' and 

 "On the crystalline nature of glass," will be published shortly in one 

 of the scientific journals of the country. The means for carrying on 

 physical research at the Institution have been materially diminished, 

 on account of the destruction by fire of the very valuable collection 

 of physical apparatus. Fortunately the cenflagration did not extend 

 to the laboratory, and consequently the chemical apparatus was pre- 

 served. 



Collections of specimens of natural history, &c. — The work of making 

 collections of specimens of natural history has been prosecuted as in 

 previous years. A very large collection of mammals, birds, eggs, 

 &c, made in the northern part of British America in 1863, princi- 

 pally by the officers of the Hudson's Bay Company, has arrived at 

 Fort Garry, and is expected soon to be received in Washington. 

 Collections have also been received from Labrador, Puget's sound, 

 and from various parts of the United States, Central America, 

 Mexico, and the West Indies, a detailed account of which is given in 

 the annexed report of Professor Baird. Advantage has been taken 

 of every exploring expedition which has been sent out by govern- 

 ment, and in many cases of the assistance offered by officers of the 

 army, particularly of the medical department, for adding new mate- 

 rials or duplicate specimens to the collections. The great object, as 

 has been frequently stated before, of this work, is to obtain the ma- 

 terials for an extended knowledge of the natural history of this con- 

 tinent, and to furnish illustrations of type specimens to museums, 

 colleges, and other educational establishments. 



The whole number of specimens catalogued during the last twelve 

 years is upwards of 100,000. and including duplicates, the whole 

 number collected will amount to five times that amount. 



