Formation of Ocean-beds by Deformation of Spheroid. 6 1 



we may have several corresponding inverted veils of darkness, 

 like blue rays in the sky, all apparently converging towards 

 the same point below the horizon. This apparent convergence 

 of the beams is merely an effect of distance, as in the case of 

 parallel rays of light from the rising or setting sun, the blue 

 rays being practically parallel bands in the atmosphere devoid 

 of illumination. It will be evident that conical-shaped clouds 

 are not necessary to produce this effect. Isolated clouds of 

 any massive form would be sufficient to throw the bands of 

 shadow through the illuminated atmosphere, and refraction 

 and perspective would do the rest. The above phenomenon is 

 called by the Singhalese " Buddha's rays ;" and though accord- 

 ing to Sir Emerson Tennent it is very varied in character and 

 appears in different parts of the sky, yet I have only seen it 

 when the sun was low at evening and when the rays con- 

 verged to a point, apparently directly opposite the sun ; and I 

 do not think it possible for the phenomenon to be seen in any 

 other position. 



VIII. Formation of the Ocean-beds by Deformation of the Sphe- 

 roid. By Robert Mallet, F.R.S.* 



IN a paper read before the Cambridge Philosophical Society, 

 February 22, 1875, by the Rev. 0. Fisher, entitled "On 

 the Inequalities of the Earth's Surface as produced by Lateral 

 Pressure, upon the hypothesis of a liquid substratum " (Camb. 

 Phil. Trans, vol. xii. part 2), for a copy of which I have been 

 quite recently indebted to the politeness of the author, I find 

 the following: — " If solidification of our globe from a fluid state 

 commenced at the surface, the amount of radial contraction in 

 the solid parts beneath the surface of the mountain-region has 

 been less than in the parts beneath the sea-bed. In fact it is 

 this unequal contraction which appears to have caused the hol- 

 lows in the external surface, which have become the basins into 

 which the waters have flowed to form the ocean." These views 

 of Archdeacon Pratt's (Figure of the Earth, 1871) appear to 

 be adopted by the author, who proceeds : — " Mr. Mallet, in his 

 paper on Volcanic Energy (see Phil. Trans. Roy. Soc. 1873, 

 part 1, paragraphs 52 to 56), takes a similar view. He thinks 

 that the land and sea boundaries were shaped out by radial 

 contraction during the first great stage of the operation of re- 

 frigeration, while the crust was thin and flexible, owing to the 

 rapid contraction of its viscous portion which must then have 

 been much thicker than the solid sheet above it." It seems to 

 me that I am thus, when taken in connexion with the rest of 



* Communicated by the Author. 



