DEEP-SEA EXPLOKATION. 
295 
THE SIGSBEE SOUNDING-ROD. 
The next nuii’ked iinprovement was made by Lieut. (-oTumaiider 0. I). Sigsbee, 
U. S. N., while in command of the ITnited States ( 'oast Survey steam(*r Blake I'rom 1871 
to 1879. Following' in the footsteps of Belknap and eonveisant with liis work on tlie 
'J'uscarora, he was in a particularly favorable position to take np the general sobject 
of improved appliances and methods in deep-sea sounding. 
The Blake had a Thomson maidiine for sounding with wire, which Sigsbee used 
with great success in his extended examination of the Gulf of Mexico. The tirst of 
his many improvements in deep-sea apparatus was a detacher which he used in con- 
nection with Belknap’s cylinder ISTo. 3, followed by a design of his own, a moditication 
of Belknap’s ISTo. 2, which after much experience he considered su|)erior to the former for 
deep-sea work. Regarding this, Sigsbee says (Deep-Sea Sounding and Dredging): 
The results of my experiments showed that a sim])le cylindrical pipe, open at hoth ends, could 
he plunged far into the sand, which, however, resisted the blunter forms to a degree that precluded 
their adoi)tion. Here was a suggestion — to shape the specimen cup as nearly as iiossible like an open 
cylindrical pi)ie; to drive it into the l>ottom material, and to retain the inclosed specimen. Bel- 
knap’s sounding cylinder No. 2 seemed to answer the demands hettei' than anything else, tlie poppet- 
valve hei]ig, to my mind, preferable to the lintterlly-valve whitdi is sometimes used. Accordingly, 
cylinder No. 2 was modified by me in some respects, and fitted with the Sigsbee detacher, after which it 
was bronght into service on board the BJakc. The spring, the cone toxi, and the fittings for peruutting 
the esca]te of water are changed somewhat from Cax>tain Belknax>'s xdan, but their operation is, in 
effect, al)out the same. It is not intended that this rod shall get a sx>ecimen of bottom water. 
He enumerates the requirements for a perfect sounding-rod, as follows: 
1. Certainty of not detaching the sinker during the descent. 
2. Certainty of detaching on striking any character of bottom. 
3. Certainty of not rehooking or of fouling with the sinker, in any way, after the same has once 
been tri])xied. 
4. Adax)tability to getting a sx>ecimen from the various kinds of bottom material. 
5. Certainty of not gra])pling irretrievably with the bottom. 
fi. Certainty of retaining the specimen against the wash of water in the ascent. 
7. Handiness for extracting the sx>ecimen and for cleaning the xmrts. 
8. Freedom from (dianging its form under the severe x^ressure in deex' water. 
9. Strength, simx)licity, cheaxmess, light weight, and freedom from corrosion. 
In general there are two ways of detaching a sinker from its rod: (1) By actual 
or partial slacking of the sounding wire or rope. (2) Directly by the impact of the 
rod against the bottom. The former method is regarded as safer, but sometimes both 
are involved in one detaching apparatus. The detacher which dei)ends for trip)»ing 
solely on the resistance of the bottom matei'ial is usually more sensitive on liard than 
on soft bottom; also, should the sinker glance on the side of a rock or ledge the trigger 
or other api)liance might not be xw'esented fairly to the blow necessary to u})set the 
connection which holds the sinker in jjlace. 
The action of the original detacher by Brooke was based on the elimination of the 
tension on the line. Tliis is the ixrinciple axixdied in the Sigsbee detacher, and, indeed, 
in almost all others aj^proved by persons of experience in deep-sea sounding. 
Remarking upon the construction of the sounding-rod, he says: 
1. The xiawl and tumbler are made to iit each other iii such a maimer that, when couuected and 
under strain, they are held umleviatiugly as shown in figs. 1 and 2 — that is, the wire is in tlie pro- 
longation of the axis of the rod. If this be not observed the relation of the leverages of the x'aw 1 
and tumbler will be destroyed and tlie detacher may be too sensitive, besides which the rod may 
incline to a degree that will act somewhat against a vertical de.scent. 
