REPORT OF THE SECRETARY. 13 



The memoirs may be written in English, French,, German, Spanish, or Italian. 

 They should be submitted either in manuscript or typewritten copy, or if in 

 type, printed as manuscript. If written in German they should be in Latin 

 script. They will be examined and the prize awarded by a committee ap- 

 pointed by the Secretary of the Smithsonian Institution in conjunction with 

 the officers of the international congress on tuberculosis. 



Such memoirs must not have been published prior to the congress. The 

 Smithsonian Institution reserves the right to publish the treatise to which the 

 prize is awarded. 



No condition as to the length of the treatises is established, it being expected 

 that the practical results of important investigations will be set forth as convinc- 

 ingly and tersely as the subject will permit. 



The right is reserved to award no prize if in the judgment of the committee 

 no contribution is offered of sufficient merit to warrant such action. 



Memoirs designed for consideration should be addressed to either " The 

 Smithsonian Institution, Washington, D, C, U. S. A.," or to " Dr. John S. 

 Fulton, secretary-general of the international congress on tuberculosis, 714 

 Colorado Building, Washington, D. C, U. S. A." Further information, if de- 

 sired by persons intending to become competitors, will be furnished on 

 application. 



Charles D. Walcott, 

 Secretary of the Smithsonian Institution. 



As a committee to award this prize the following gentlemen have 

 consented to serve : Dr. William H. Welch, of Johns Hopkins, chair- 

 man; Dr. John S. Fulton, secretary-general of the congress; Dr. 

 Simon Flexner, director, Eockefeller Institute for Medical Kesearch, 

 New York ; Dr. George M. Sternberg, Surgeon-General, U. S. Army, 

 retired; Dr. Hermann Biggs, New York department of health; Dr. 

 George Dock, of the University of Michigan; and Dr. William M. 

 Davis, of Harvard. 



flow of aie at high pressure through a nozzle. 



The inquiry to determine the cooling effect of the nozzle expansion 

 of air for large pressure differences, which has been conducted by 

 Prof. W. P. Bradley, of Wesleyan University, with the aid of a grant 

 from the Hodgkins fund of the Institution, is announced as nearing 

 completion. The investigation was intended specifically to determine 

 whether the cooling process is due to the Joule-Thomson effect or to 

 the performance of external work by the expanding air in pushing 

 back the atmosphere from before the nozzle. The results of the in- 

 quiry make it clear that pressure is an important factor and that the 

 cooling effect increases very rapidly indeed as the initial temperature 

 falls. Professor Bradley is now engaged in an exact mathematical 

 discussion of this research. 



As to the apparatus employed, an interchanger of the Hampton 

 type was so constructed, in vertical sections, that the amount of 

 interchanger surface in actual use could be varied at will, from noth- 

 ing to more than enough to induce liquefaction. In this manner it 

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