16 REPORT OF THE SECRETARY. 



of knowledge. During the past year an appropriation lias been made 

 of one hundred dollars for the purpose here mentioned, and we are 

 assured, from what Mr. Meech has already accomplished, that this 

 sum will be instrumental in producing valuable results. He proposes 

 to determine, from several elementary formulas, the laws of terres- 

 trial temperature for different latitudes. The first formula has been 

 pretty thoroughly applied, and the annual temperature computed by 

 it compared with the result of actual observation. The diurnal 

 temperatures have also been deduced and seem to agree with actual 

 observation within the presumed errors of the latter. The temper- 

 ature, however, of the surrounding medium, defived from the annual 

 temperature, differs widely from the results obtained by the diurnal 

 temperatures. The author is inclined to attribute this difference to a 

 defect in the law of radiation as generally received, which, deduced 

 from experiments in the laboratory, he thinks inapplicable to the 

 phenomena of terrestrial temperature. The second formula takes into 

 account another cause of the variation of temperature, namely, the 

 cooling due to the contact of the air ; and the third formula includes 

 also the effect of the absorption of solar heat in its passage through 

 the atmosphere. The investigation will include the consideration of — 

 1st, terrestrial radiation ; 2d, contact of air ; 3d, the sun's intensity ; 

 4th, atmospheric absorption ; 5th, the difference in radiating power of 

 luminous heat by day and non-luminous heat by night. Among 

 other inferences to be deduced is the relative heating or radiating 

 powers of sea and continent, when the land is covered with foliage 

 and vegetation, and when it is covered with ice and snow. These 

 researches are intimately connected with the extended series of obser- 

 vations on the climate of the United States, now carried on at the 

 expense and under the direction of the Institution. 



The paper of Professor Gibbs and Dr. Genth, which forms a part of 

 the 9th volume, has been republished in the American Journal of 

 Science and in the London Chemical Gazette, due credit being given 

 to the Smithsonian Contributions, from which it was copied. We 

 regret to be informed by the authors of this interesting paper that 

 the sum appropriated by the Institution for assisting in defraying the 

 expense of the materials and apparatus employed in their researches 

 was scarcely sufficient to compensate for more than one-fourth of their 

 outlay. Limited means, and not a want of proper appreciation of the 

 labors of these gentlemen, prevented their entire reimbursement for 

 the pecuniary loss in the prosecution of their valuable researches. 

 They intend, notwithstanding this, to continue their investigations, 



