RIVEE VALLEYS OF THE WEST AFRICAN CONTINENT, ETC. 161 



own experience while fishing up and repairing broken telegraph 

 cables. Cable repairing, requiring as it does close and careful 

 survey, necessitates sounding at distances of perhaps half a mile 

 apart, whereas in ordinary deep sea surveys for cable laying 

 purposes sounding at distances of 10 to 12 miles apart have been 

 considered sufficient. This close examination of the bottom by 

 sounding enables us afterwards to draw contour lines that map 

 out the configuration of the ground upon which the cable lies, 

 and this has been our practice for the past 20 years. Sometimes 

 we find it to be variable and unevee. This survey forms a very 

 interesting study in itself, apart from the exigencies of cable 

 operations, and one is loth to confine it to the area of the work 

 in hand. I have wondered that the owners of steam pleasure 

 yachts have not emulated the example of the Prince of Monaco, 

 Mr. Coats, and a few others, and have taken up this subject as a 

 pleasant and interesting field of research, the outfit required being 

 light, simple, and comparatively inexpensive. The soundings 

 taken over the Bottomless Pit by the Silvertown Company's 

 telegraphic steamer Bree in 1886, and to which Professor Hull 

 refers, were under the supervision of Mr. J. Y. Buchanan. The 

 latest corrections show the width of this gully at a mile and a 

 half from the shore to be less than one mile, with a depth of 

 170 fathoms. At about 7 miles from shore, the width is 2 miles, 

 with a depth of 327 fathoms. At about 9 miles off, it widens to 

 nearly 5 miles with a depth of 4^2 fathoms. The slopes of the 

 sides averaged in some parts 2,000 feet per mile. During cable 

 repairs in other localities more or less similar features to these 

 have been met with, notably in vicinity of Cape St. Vincent and 

 of the supposed sub river outlet of River Parvinas, North Peru ; 

 but I think the most remarkable instance that 1 know of, and one 

 outside cable work, is the depression called on the Admiralty 

 charts, "the Swatch, of no ground" off the mouth of the Ganges. 

 This gully formation is frora 6 to 12 miles wide, with a maximum 

 depth of close on 600 fathoms, with 75 and 80 fathoms to each 

 side. From the fact of these submarine gullies existing, I am 

 inclined to the belief that in some instances they are evidence, 

 not only of possible ancient river courses, but of probable present 

 outlets for freshwater escapes beneath sea level. 



Commander Heath, R.N. — The formation of the deltas of rivers 

 is pretty well known to us, and they are formed at all rivers by the 



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