40 EEPOKT OF THE SECRETARY. 



MISCELLANEOUS. 



At a meeting of the British Association in 18G8 a committee was 

 appointed for the purpose of obtaining observations in various localities 

 on the rate of increase of underground temperature downward. This 

 committee (through its secretary, Prof. J. D. Everett) has requested 

 the Institution to furnish observations on this subject from the United 

 States. 



These observations are generally made by noting the temperature in 

 artesian v.ells; and although a large number of these borings for water 

 have been made in this country, the precautions to be taken, and the 

 skill required, in obtaining the true increase of temperature in relation 

 to the depth are of a character not to be intrusted to ordinary obser- 

 vers ; and, therefore, to meet the requirements of the committee, a special 

 agent will be necessary to visit the different localities. The income of 

 the Institution, up to this time, has not permitted the incurring of the 

 cost of such an agency, although we hope in the future to be able to 

 make an approprintion for the purpose. In the mean while we have 

 intrusted a set of four standard thermometers, furnished by Professor 

 Everett, and compared at the Kew Observatory, to Mr. B. D. Frost, 

 engineer of the Hoosac Tunnel, Massachusetts. 



The investigation is one of great interest to the geologist, being inti- 

 mately connected with the hypotheses concerning the geological changes 

 to which the globe, has been subjected. The fact has been fully estab- 

 lished that, in every part of the world where observations have been 

 made, after descending a few feet below the surface or beyond the 

 depth at which the temperature of the ground is aftected by variations 

 in the solar heat, there is a gradual increase of temperature varying in 

 the rate of increase at different places, but ou an average not lar from 

 one degree iu every sixty feet, or a rate which, if continued, would indi- 

 cate the fusiug-point of iron at a depth of about twenty-eight miles. 



At the last meeting of the Board the subject of the desirability of 

 the franking privilege to the Institution was discussed, as it had fre- 

 quently been at previous meetings. Hon. Mr. Hamlin, who is a member 

 of the Post-Oftice Committee of the Senate, offered to endeavor to pro- 

 cure action of Congress in regard to this object, and accordingly at 

 the last session the following law was enacted. 



" All publications sent or received by the Smithsonian Institution, 

 marked on each package ' Smithsonian Exchange,' shall be allowed to 

 pass free in the mail." (Kew Postal Code, Gth subdiv., 183d sec.) 



It will be seen from the above that the franking privilege is confined 

 to printed matter, and does not relieve the Institution from the burden 

 of its large letter-correspondence, and, above all, from a new and unex- 

 pected source of expense in the mineral specimens which, since the 

 transfer of the collection of the Land-Oitice to the museum of the Insti- 

 tution, are sent by mail from the different Government surveyors. We 



