60 THE ATLANTIC. (CHAP. I. 
has already produced a large number of very satisfactory pict- 
ures. 
Hundreds of miles of line, of strength and material suited to 
different purposes, are reeled and coiled in every available spot 
on the forepart of the main-deck and elsewhere. When we 
left England, we were provided with 25,000 fathoms of bolt- 
rope for the dredge, 10,000 fathoms 3-inch rope, 10,000 fath- 
oms 24-inch, and 5000 fathoms 2-inch, and the supply has since 
been renewed. The methods of sounding and dredging, and 
the appliances used, are very much the same as those which we 
employed in the Porcupine, and which I have described fully 
in a former volume.* For deep sounding we now very gener- 
ally use a neat modification of the “ hydra” machine, devised 
by Navigating- Lieutenant C. W. Baillie. The “ Baillie” 
sounding instrument is represented in perspective in the posi- 
tion in which it is let go in Fig. 14, A, and in section in the 
same position at B. The tube a@ is about 5 feet 6 inches in 
length by 23 inches in diameter. The bore is 2 inches, so that 
the wall is 4 inch thick. The principal part of the tube is of 
iron. It is bored near its upper end with a number of holes 
to let out the water ; it unscrews into two at e, and at its lower 
end, f, there is a pair of butterfly-valves working inward. A 
strong brass cylinder, 6, with a diameter equal to that of the 
tube, is firmly attached to the upper end; a heavy piece of 
iron, c, works in the brass cylinder like a piston to the extent 
of the length of the slots, d, in the sides of the cylinder, in 
which it is retained by a strong square bolt. The piston-iron 
is flattened, and it is provided at ¢ with a projecting shoulder, 
which, when the piston is drawn out—the bolt being at the top 
of the slot as in the figure—is well above the top of the cylin- 
* “The Depths of the Sea: an Account of the General Results of the Dredging 
Cruise of H. M. Steamships Porcupine and Lightning during the Summers of 1868, 
1869, and 1870, under the Scientific Direction of Dr. Carpenter, F.R.S., J. Gwyn Jet- 
freys, F.R.S., and Dr. Wyville Thomson, F.R.S.” London: Macmillan and Co., 1873. 
