W. P. Trowbridge on a new Sounding Apparatus. 5 
- Secondly, a rapid and uniform descent being secured, the indi- 
cations of a revolving register will be reliable when attached to 
this plummet; while in the present mode of sounding the slow’ 
motion of descent at great depths, renders such a mode of regis- 
tering the depth uncertain and unreliable. 
hirdly, there being no strain upon the line in the descent and 
the motion being uniform, it is practicable to determine the 
depth by the time of descent, making use of a small insulated 
wire as a sounding line, and determining the instant that the 
weight strikes the bottom by an —— signal transmitted 
throu gh the line. An apparatus was devised as long since as 
the year 1845, for ascertaining the apehetst when the weight 
strikes the bottom, by electricity, but in the mode of soundin 
heretofore employed, no particular advantage would result from 
this, while the danger of breaking the electric continuity is very 
great owing to the strain brought upon the line in the descent ; 
and the plummet as now used descends with such a varying 
velocity, oe even with the time of descent given, no calculation 
will give the depth. e method has therefore never been put 
in preictios: Whereas, in the method proposed, there is no 
strain upon the line in its descent, and the plummet will fall 
through each successive hundred fathoms in the same time ; the 
time cof descent = thus furnish a simple means of calculating the 
tn ‘this process it will not be n necessary to recover the line, and 
the time required to sound the ocean at any point, need only. be 
that required for the plummet to sink to the bottom, moving 
with any velocity whith may be desired. 
ave made many experiments on the best method of ae 
the line so as to secure its uncoiling with certainty, and wi 
the possibility of strain upon the line, or the occurrence of a ‘sede 
ave also given much attention to the quality and size of 
wim to be used: upon these _ the pe tical working of the 
question has abiins e one sof great ‘public interest in connection 
with the laying of submarine telegraphs; the risk of such enter- 
ge being diminished in proportion to the accuracy with which 
th of the sea is known at every point of any proposed 
