298 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
of great value providing it iiisured uninterrupted continuance of operations, and it is 
liardly reasonable to supi»ose tliat a vessel conducting extensive deep-sea sounding 
would be without the necessary materials with which to construct some siinjile and 
fairly elfective form of rod. 
THE SIOSBEE GAS-PIPE SOUNDING-ROD. 
In the deep waters of the G ulf of Mexico, where large bottom specimens were not 
require<l, Sigsbee used a , sounding-rod of one-half-incli to three-fourths-inch gas pipe, 
20 inches in length, with a Sigsbee detacher screwed into one end, and in the other a 
metal ball valve to retain a small bottom specimen; an arming of tallow may be used, 
but tlie valve is iireferable. Additional length is given the 
cylinder to insure prompt action of the detacher when the 
shot reaches the bottom. A ball of lead or other metal 
inserted in the pipe with one-eighth-inch clearance and the 
lower end of the latter upset sufticiently to form a valve seat 
will answer the purpose; there should be a couple of small 
holes in the pipe near the upper end for the escape of air and 
water. Tliis rod being inexpensive, light, and offering little 
resistance when reeling in, may be used to advantage under 
the exce])tional circumstances before mentioned. 
EMERGENCY SOUNDING-RODS. 
Sounding-rods of this description would be used only 
when the regular supply became exhausted, and, being hur- 
riedly improvised, perfect action or thorough reliability could 
not be expected. They may be made of iron or brass pipes, 
spare condenser tubes, iron rods, or flat bars, i)roviding they 
have the necessary rigidity. The gas-pi])e rod has been 
described, and if the facilities are at hand for making the 
Sigsbee detacher an elfective sounding-rod is assured, other- 
wise there is left a choice between the two forms of Brooke 
apparatus, the double and single arm detachers. 
THE BROOKE DOUBLE-ARMED DETACHER. 
While this form is not as readily operated or as reliable 
as the single arm subsequently introduced by Brooke and 
generally adopted, it is the most readily improvised with the 
facilities usually found on shiplioard, and deserves a short description. 
It is composed of two Hat arms, alike in every respect, each having a hole through 
its lower end for a j)in upon Avhich they work, a hole through their upper extremities 
to which the bridle is attached, and lips on their outer edges from which to suspend 
the sinker during its descent and release it when it strikes bottom. 
The single arm detacher has already been described with the Brooke deep-sea 
sounding apparatus. Belknaj) adopted it, and next to the Sigsbee it is the most 
reliable. Its construction is comparatively simple, providing the points ot sus])ension 
are maintained in prolongation of the axis of the rod, as shown in the description of 
Ci'T 29. — 9’lie Brooke doiil)le 
arm detarher. 
