= 
158 W. P. Trowbridge on Deep Sea Soundings. 
16 feet per second for a 32 pound shot and sa feet fora 95 p 
Maas such as was used by Lieut. Com. Daym i 3h 
en the line begins to offer resistance a the motion, the veloc- 
ity is "rapidly “apie becoming at the depth of 2000 fathoms only 
two or three feet per second, and at 3000 fathoms, still less. _ 
3d. This diminution of velocity i is due entirely to the resistance offer 
by the line, the resistance offered by the sinker being at the dey of 
2000 fathoms only a fraction of a pound, while that of the lines amounts ~ 
to nearly the whole weight of the sinker; the excess of the weight of the 
sinker being sufficient to impart a very small velocity to the line. 
e resistance upon the line varies, Ist as the @ sequare. 0 the 
Maite £ 2nd as the diameter of the line, 3d as the len ine im- 
ew th. ‘The variations of gravity do not sensibly affect the rate of sift 
6th, The variations of density do not increase the resistance at g 
depths, but it appears that 8 which are “iene will fall mo 
a at joes depths than a ee. 
th. The est line that can be used with safety will 
Roane secintilinn to support nearly the whole weight of | oi are heaviest a 
sinker at considerable depths. ae is 
8th. The probable errors of results where the length of line paid out a 
is . as the depth, are so great that this method is the most unreliie eo 
| for determining the dep : = 
. 9th. The method of ascertaining the depth by Massey’ s Indicator is the” 
E best that has been devised, provided the indicator be always ih. 
the same line and weight. This method however has also been very UD- 
satisfactory, giving large errors on account of the faulty construction of 2: 
the machines - 
10th. The results of Lieut. Com. Dayman were obtained from the ¢ 
Sort method, those of Lieut. Com. Berryman by the Indicator, and - 
therefore Berryman’ s results are undoubtedly nearer the truth than Day- 
man’s, but from neither can the existence of a “plateau” between News> 
foundland and Silend be made out. 
There is yet, it seems to me, nothing to show that the bottom of the 
sea presents features any different from the face of the country across an, 
ae of our eee: except perhaps the highest mountain ae 
. Highlands of the Hudson, fori ecg would be unnoticed in hi ‘a 
“ plateau.” 
11th. To obtain correct none some improved m ethod of re 
the depths seems to be necessary, and I would respectfully yges 
sieation iol 2 of Mr. Saxton’s sommes Indicator to suit the circumstances 
the case. 
_ I would also beg leave to suggest the coiling. of the lina ee a bk 
wea eget is ie be attached to the weight, so that the 
Ys y means the resistance —— 
he water, will be avoided. If ger be panicle, a 
ay be and the wei will desqang tarongh 
all 
