2a 



PROCEEDINGS. 



APRIL 12th, 1883.— OEDINAEY IIEETING. 



ME. WM. BOULTING, L.E.C.P,, 



President, in the Chair. 



The Minutes of the preyious meeting were read and confirmed. 



The donations to the Maseum were annouaced and the donors thanked - 

 Miss James pre-sented to the Library, " The Collected Papers of Garrod," 

 and a vote of thanks was accorded her. 

 Two gentlemen were proposed for membership. 



MR. A. C. CLAUDET, A.R.S.M., read a paper on " THE INTERIOR OF 

 THE EARTH." He commenced by mentioning the vague ideas generally 

 held with regard to the conditioH of the isteriorol our globe. There is, how- 

 eTer, one thing certain — although our absolute knowledge of the interior is 

 small — and that is, that at some depth beneath o»r feet there exists great heat. 

 Ccnlirmation of this is everpvhere to be obtained, for in the sinkisg of shafte 

 for mines and wells, and in the borings made in varioas parts of the world, an 

 increase of temperature always occurs as greater depths are attained. The 

 average increase of temperature, as deduced from many experiments, has been 

 estinwted at 1 deg. Fahr. for every sixty feet of descent. The form of the earth 

 —an oblate spheroid— is that which would be assumed by the gradual eoolcng 

 of a molten body. The nebular theory of the univer^ie was explained, showing 

 that the sun was the nucleus of a luminous mass which revolved on its axi.s, 

 and extended far beyond the orbits of the most distant plaaeLs, which at that 

 time were not formed. The diminution of temperature caused the nebulae to 

 contract, and the rapidity of rotation caused portions to be thrown off, and 

 the further condensation of these detached masses formed the planets and 

 satellites. The proofs of internal lieat are yolcanos and earthquakes, hot 

 .springs, borings, wells, and mines. Each of these was then explained, and 

 the theories of volcanic action discussed. The importance of the examina- 

 tion of meteorites as helping to solve the problem of the composition of the 

 interior of the earth was described. The greater density of the earth, as a 

 whole, compared with the rocks at the surface, leads to the idea that metallic 

 substances, probably iron, abound near the centre. The various theories of 

 the condition of the interior of the earth, resulting from a slow cooling of a 

 molten mass, were discussed. Some supposed it to have solidified at the 

 centre and crust at the same time, others maintaining that the interior is 

 liquid and confined by a thin shell or crust of a thickness varying from fifty to 

 two hundred miles. The lecturer then stated the theories of volcanic action, 

 and referred especially to the theory that some metals, when under certain 

 conditions of temperature and pressure, are able to absorb many times their 

 volume of certain gases, and, on cooling, these gases are given off or occluded. 

 Molten silver absorbs oxygen from the atmosphere, and on cooling gives it 

 out again with considerable force. This " spitting " of silver, as it is termed, 

 resembles very closely the action of a volcano, small cones and streams of 

 metal being formed very like those in volcanic regions. At the conclusion of 



