32 Prof. J. W. Judd. Second Report on Specimens 



been made to look for any kind of motion except such as would be 

 •caused by something akin to viscosity. 



Incidentally the author points out that by rotating the whole optical 

 apparatus and observer, instead of the disks, at a very moderate speed, 

 a shift of the bands should be seen ; and even that the earth's rotation 

 would with a large enough frame produce an effect, which latter, 

 however, it appears difficult or impossible to observe, not on account 

 of its smallness, but on account of its constancy. 



The effect to be expected on Fresnel-Fizeau principles from whirling 

 air, was unfortunately just too small for the author to safely observe. 

 The residual disturbing causes just masked it, but it is probably not 

 beyond the reach of another attempt with a still more thoroughly 

 steady machine, if anyone feels inclined to persevere so far. At the 

 same time if it be supposed that any microscopic trace of true ether 

 effect still possibly exists (which the author wholly disbelieves), and 

 if a further attempt be hereafter made to observe it, a number of 

 slight residual disturbing causes would be got rid of (and probably 

 other difficulties introduced) by rotating the machine in a vacuum. 



■" Second Report on a Series of Specimens of the Deposits of 

 the Nile Delta, obtained by Boring Operations under- 

 taken by the Royal Society." By John W. Judd, C.B.. 

 LL.D., F.R.S., Professor of Geology in the Royal College, 

 of Science. Communicated by desire of the Delta Com- 

 mittee. Received February 11, — Read March 4, 1897. 



The last report on the borings undertaken in the delta of the Nile 

 under the auspices of the Royal Society was communicated to the 

 Society by the direction of the Delta Committee on November 12, 

 ]885, and published in No. 240 of the 'Proceedings.' This report 

 dealt with the materials obtained from the three borings made at 

 Kasr-el-Nil, at Kafr-ez-Zayat, and at Tantah, which reached depths 

 •of 45 feet, 84 feet, and 73 feet respectively. Although these borings 

 made known to us the character of the delta deposits at greater 

 depths than the explorations made by Mr. Leonard Horner and M. 

 Linant de Belief ondes, yet none of them succeeded in reaching the 

 solid rock on which these deposits lie, and in which the Nile Valley 

 was originally excavated. It was therefore decided by the Delta 

 Committee to make still more strenuous efforts to attain this result — 

 a result which the sections published by Figari Bey, said to be based 

 on borings made for the purpose, led the Committee to believe might 

 be arrived at with a moderate expenditure. 



In their attempts to carry out this important work, the Delta Com- 



