Sea Log and Sounding Machine . # I2i 
ty, lie still cannot depend upon the truth of his soundings ; 
for if there be the Iqast drift or current, the line itself will 
assume a curve, similar to that of the line of a kite in the 
air. These two causes will always operate against the 
perfection of the common mode of sounding. 
After so fully describing the principle of the patent 
sounding machine, it is scarcely necessary to prove, that 
it is liable to neither of the foregoing objections; and it 
may be sufficient to say, that, as it will certainly find its 
way to the bottom, if a sufficient portion of stray-line be 
allowed to guard against its being checked in its pro- 
gress, and the certainty of its having reached the bottom 
may be ascertained by the arming, there can be no doubt 
of the practicability of its obtaining soundings, in any 
depth, and no reasonable doubt of their correctness when 
obtained. 
From the construction of this machine, it might be 
imagined, that the rotator would impede its motion 
through the water, and that it could not descend so rapid- 
ly as the common lead ; but during repeated trials, in 
thirteen fathoms water, in which the rotator was fre- 
quently detached, and the lead suffered to descend alone, 
there was no difference perceptible in the time of their 
descent, though an excellent quarter-second stop watch 
was used during the experiment, to detect any change. 
The following table shows how very uniformly the times 
of descent corresponded with the depths in fathoms, dur- 
ing a series of trials made on the river Mersey, with the 
patent lead, weighing fourteen pounds. 
The manner of conducting these experiments was such 
as is deserving of perfect reliance. Two pilots, of well 
known ability and experience, were employed : one 
threw the lead, and the other, the moment he found, by 
the slackening of the rope, that the weight had arrived at 
Vol. II. p 
