104 ON ROCK REMAINS IN THE BED OF THE ENGLISH CHANNEL. 



The disposition of the samples is as follows : — 



5-10 miles 8., Magnetic 1 sample . 



10-15 „ „ 18 samples 



15-20 „ „ 13 „ 



20-25 „ „ 3 „ 



25-30 „ „ 7 „ 



30-35 „ „ 7 „ 



35-40 „ „ 2 „ 



The area between 20 and 25 miles, represented by three samples, should 

 properly include the sample (74) previously referred to, where the 

 stop of the dredge being broken, owing to the roughness of the ground, 

 no numerical results were obtainable, and the position had therefore 

 to be left out of consideration. There is little doubt therefore that it 

 is owing to an insufficient number of samples that a drop occurs over 

 this area in both curves. 



In point of size and weight, then, there is a steady increase 

 correlated with distance in a mid-Channel direction. For the loca- 

 tion of the samples, the bearing and distance of all the positions 

 has been reduced to the Eddystone ; but the main bearing of the 

 work being S, 23° W. from this point, that is, almost directly on 

 Ushant, their location must be regarded from a different standpoint, 

 where questions are involved relating to their distance from the 

 English coast. Treating the Eddystone as an outlying point on the 

 coast-line, a line running through it E. and W., Mag. will be roughly 

 parallel to the mid-Channel line, and less than one point off the main 

 direction of Hurd Deep. Outside it the positions fall naturally into 

 the groups from which the curves (Figs. 1 and 2) are obtained at 

 5-mile intervals, as follows : — 

 5-10 miles. 37. 



10-15 „ 36, 31, 32, 35, 33, 34, 10, 11, 12, 13, 39, 40, 9, 16, 15, 

 72, 26, 27. ♦ 



15-20 „ 14, 20, 21, 22, 29, 30, 34, 25, 17, 19, 18, 42, 41. 



20-25 „ 73, 74, 43, 47, 44. 



25-30 „ 55, 56, 53, 44, 50, 51, 58. 



30-35 „ 58, 75, 67, 76, 77, 63, 62. 



35-40 „ 79, 80. 



In connection with the foregoing deductions, two points may here 

 be considered : (1) the size of the stones in relation to that of the 

 opening of the dredge frame ; (2) the position in which they lie. 



In regard to the first point, the 3' 6" dredge, the largest used, with 

 a frame of 3' 6" x 1' 0", offered an opening of about 100 x 30 cm. 

 Similarly the 3' 0" and triangular dredges allowed of stones at least 



