Reports & Proceedings — The Royal Society. 283 



following redistribution of mass by erosion and deposit. It is pointed 

 out that in the Sierra Nevada and in the Coast Ranges denudation is 

 very active, while most of the material thiis set free is deposited 

 either in the Great Valley of California or in the sea close to the 

 coast. The overloading must be specially conspicuous in and near 

 San Francisco Bay. Owing to this overweighting the areas of 

 deposition undergo down-warping, while the denuded areas tend to 

 rise, thus involving a compensating creep in the plastic depths. It 

 is concluded from various lines of evidence that this creep or 

 undertow must be greater in a direction parallel to the axes of the 

 ranges thau perpendicular to these ; accordiugly a state of tension is 

 produced highly favourable to the formation of slip-faults with 

 lateral displacement, such as the one that formed so conspicuous 

 a feature of the San Francisco earthquake. A considerable amount 

 of subsidiary evidence is put forward in support of the main idea, 

 partly physiographic, derived from a study of Californian topography, 

 and partly geodetic, depending on the results of many elaborate 

 investigations of anomalous distribution of gravity and allied 

 phenomena in this part of the United States. 



11. H. E. 



E,E:P0E.TS .A.3SriD :E=I?,OOEE!IDID^TGrS. 



I. — The Royal Society. 

 April 25, 1918. — Sir J. J. Thomson, O.M., President, in the Chair. 



The Bakerian Lecture was delivered by the Hon. Sir Charles 

 Parsons, K.C.B., F.R.S., on " Experiments on the Production of 

 Diamond ". 



In his lecture the author alluded to some of the results of 

 experiments described in papers by him to the Royal Society in 1888 

 and 1907, more particularly to those on the decomposition by heat of 

 carbon compounds under high pressure, and on the effect of applying 

 pressure to iron during rapid cooling. 



A description is given of experiments designed to melt carbon 

 under pressures up to 15,000 atmospheres by resistance heating and 

 by the sudden compression of acetylene oxygen flame, also by the 

 firing of high velocity steel bullets through incandescent carbon into 

 a cavity in a block of steel. 



Allusion is made to experiments on chemical reactions under liigh 

 pressure and their results. The pressures occurring in rapidly cooled 

 ingots of iron and experiments bearing upon this question are dis- 

 cussed. Experiments at atmospheric pressure and experiments in 

 vacuo are described. 



The main conclusions arrived at are : that graphite cannot be 

 converted into diamond by heat and pressure alone within the limits 

 reached in the experiments ; that there is no distinct evidence that 

 any of the chemical reactions under pressure have yielded diamond ; 

 that the only undoubted source of diamond is from iron previously 

 heated to high temperature and then cooled; and tliat diamond is 

 not produced by bulk pressure as previously supposed, but by the 



