REPOliT OF THE SECRETARY. 11 



plaster was falling in patches from time to time, and greatly endanger- 

 ing life and property in the Museum, it was deemed best to adopt the 

 heroic treatment of taking it all down and calcimining the exposed sur- 

 face. This occupied the greater part of the summer, yiid created a 

 vast amount of dust and of refuse matter, to be taken away. This has 

 HOW been cleared up, and the rooms restored to their ijrevious condi- 

 tion. 



It has always been considered desirable to have a supplementary 

 ceiling or skin to the main ceiling, inclosing au air-space between the 

 two, for the purpose of preventing the escape of heat in winter and its 

 access during the summer, and au experimental trial was made by put- 

 ting up one section of corrugated iron. This has been found to produce 

 a very agreeable effect, and will probably tend, so far as it goes, to 

 remedy the disadvantage referred to. It would be desirable, if the 

 money could be obtained, to complete this work over the entire build- 

 ing, as the hot weather of the last summer j^roved to be extremely try- 

 ing inside of the building. Tbe introduction of some additional venti- 

 lators considerably relieved this difficulty. 



lu certain cotton mills in New England the experiment has been made 

 of moistening the air by means of a system of aspirators, for the 

 l^urpose of improving the facilities of cotton spinning. While accom- 

 plishing this object, it has been found that the reduction of tempera- 

 ture iu hot weather amounted to 8° or 10° in some cases, while at the 

 same time the air was rendered very much more agreeable as well 

 as more wholesome at all times. An offer has been made by the pat- 

 entee to appl}^ his apparatus to the National Museum at a cost of about 

 $7,000, he guaranteeing that a reduction of from six to eight degrees 

 of temperature shall be accomplished during the hot season of the year. 

 This will be a question for determination in the future. 



During the very cold weather of the winter of 1880, '81, it was found 

 that the northeastern pavilion occupied by the ethnological and geologi- 

 cal bureau was insufficiently heated, this portion of the building being 

 most distant from the furnaces. A supplementary steam furnace was 

 therefore introduced into this division. 



Thefltting and furnishing of the ]^hotographic laboratory in the south- 

 eastern building has been completed, and it is now thoroughly adapted 

 to its purposes. The operations of the Institution require a great deal 

 of i)hotographic work, which is now carried on in this building. 



The fitting up of the chemical department in the southeastern divis- 

 ion has been completed during the year. The laboratory is now fully 

 equipped aud able to perform any chemical work required. The chem- 

 ists have been constantly employed in solving problems committed to 

 them, and a great deal of excellent work has been i)erforraed. 



A special assay laboratory has been fitted up with the necessary ap- 

 l^aratus. 



Proper connections have been made in and between all the buildings 



