ADVISORY COMMITTEE ON GEOPHYSICS 59 



[^Lord Kelvin to Mr. Walcott,June 2, ipo2.'] 



15, Eaton Place, 

 London, S. W.,/?ine2, ipo2. 

 Dear Mr. Walcott : 



I was sorry not to have time to answer your letter of April 24, 

 regarding the proposed establishment of a geophysical laboratory, 

 before I left America. I had not forgotten it, and was on the point 

 of writing to you when your letter of May 1 5 , connected with the 

 same subject, reached me here. 



I am very glad to hear that there is a prospect of a geophysical 

 laboratory being founded as part of the Carnegie Institution of 

 Washington. I think it may prove most beneficial. Observations 

 of volcanic phenomena in all parts of the world might, I think, be 

 largely promoted by such an institution. Since I had the pleasure 

 of meeting you in Washington we have had a sad and terrible 

 demonstration in Martinique and St. Vincent of the great human 

 interests concerned, which should prove a great impulse to prose- 

 cuting the natural history study of the subject. 



I suppose you know of Milne's seismographic work, which he 

 commenced in Japan and is now continuing in the Isle of Wight. 

 Such work might very properly be taken in hand by the Carnegie 

 geophysical laboratory. Professor T. Gray, Rose Polytechnic In- 

 stitute, Terre Haute, Indiana, would, I am sure, be able and pleased 

 to give you good advice on the subject. He worked in conjunc- 

 tion with Milne on it in Japan. 



In respect to purely laboratory work the melting temperatures of 

 all kinds of natural rocks is a very important subject for experi- 

 ment. So is the relative density of melted rock and of solid rock 

 at the same or at slightly lower temperature. This could be done 

 most easily by melting a considerable quantity of rock in a crucible 

 and dropping into it pieces of the same rock solid, but previously 

 heated up to nearly the same temperature. It should not be a diffi- 

 cult observation to find whether they sink or swim ; except in cases 

 in which the melted rock is frothy at the surface by emission of 

 gas. 



By book post I send you with this an article on The Age of the 

 Earth, which you may have seen already, but probably without the 

 addendum at the end, which bears on geophysical laboratory work. 

 You will also see on page 75 of the print a reference to good work 

 by Dr. Carl Barus in Mr. Clemence King's geoph}^sical laboratory. 



