DEEP-SEA EXPLORATION. 
21)3 
H. B. M. S. Challen</e)' sailed on her celebrated scientific voyage around the world 
in December, 1872, six months after the introduction of Sir William Thomson’s machine 
for sounding’ with wire, and at the instance of the inventor one of his machines was 
])laced on board, but was relegated to the storeroom, where it remained during the 
entire cruise notwithstanding the remarkable success attending its introduction into 
the United States Navy and Coast Survey. 
The successful operations of the Porcupine in sounding witli rope naturally inllu- 
enced its retention on the Challenfier, whicli was amply 
supplied with the best Italian hemp No. 1 line, 1 inch in 
circumference, weighing about 200 iiounds per nautical 
mile. The Baillie sounding machine, a modilication of the 
Hydra, was adopted, and it was unquestionably the best 
device yet introduced for sounding with roiie. It differed 
from the Hydra jirincipally in the detacher, which was 
much improved; the rod remained practically the same, 
and tbe disk weights were retained. A further increase 
in the weight of sinkers to 400 pounds and upward in deep 
water, enabled them to obtain good results, although at 
the expense of much time ami labor. 
The Baillie sounding machine is described as follows 
by Sir C. Wyville Thomson: 
It is re]>reseiited in perfection in the position in wliich it is let 
go in A, and in section in same position at B. The tnhe A is ahont 
5 feet 6 inches in length hy 2^' inches in diameter. Tlie hore is 2 
inches, so that the wall is one-fourth inch thick. The j)riucipal part 
of the tube is of iron. It is liored near its upper end with a nnmher of 
holes to let out the water; it unscrews into two at e, and at its lower 
end, /, there is a pair of butterfly-valves working inward. A strong 
brass cylinder, h, with a diameter equal to that of the tnhe, is firmly 
attached to the n]>iier end ; a heavy piece of iron, c, works iu 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 scpiare bolt. 
The piston iron is flattened, and it is provided at c 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 cylinder; 
but when the piston is drawn down, and the holt at the bottom of 
the slot, the shoulder is jnst within the upper part of the cylinder. 
The wall of the upjier part of the cylinder is beveled away to a long 
rounded slope. 
When to be used, the instrument is hung by the ring to the 
sounding line, a sufficient nuinlier of weights are suspended on an 
iron wire sling, as in the Hydra machine, the tube passing through 28. Baillie sounding 
the middle of them, and the sling hooking upon the shoulder of the uiachine. 
piston iron. When the tnlie and weights touch the bottom, the brass cylinder is pushed upward the 
length of the slots, and the sling is slipped off the shoulder of the piston iron by the upper rim of 
the cylinder and allowed to slide down over its beveled upper end. This is a very simple plan, and the 
doing away with the steel spring of the Hydra is an advantage. The larger tube also brings up a 
better and fuller sample of the bottom. 
Ill the spring of 1873, a few months after tlie departure of the Challenger, the 
U. S. S. Tmcarora, Oapt. George E. Belknap, United States Navy, was fitted out for 
the fnirpose of sounding a submarine cable route from California to Japan. She was 
