DEEP-SEA exploration. 
299 
tlie Brooke apparatus, and it would i)robal)ly be the form usually adoxhed. To insure 
projier action the relative proportions of the detacher would be determined by 
ex])erimeut, and if it be made to release the weight at a tension of 10 pounds and 
hold on to it under greater strain it can not be far wrong. The Sigsbee detacher trips 
at 8 pounds, bnt it would not be advisable to give an imxu'ovised tumbler so small a 
margin of safety. 
improvised BROOKE SOUNDING-ROD. 
Sigsbee’s gas-pipe rod with Brooke’s single detacher is the simidest and most 
ettective, x)roviding suitable x)i])e is at hand; if not, an iron rod may be substituted, the 
uii|)er end split to admit the detacher, and a short i>iece of j)i]>e attached to the lower 
end for a sx)ecimen cuxi, substituting the ball valve for the goose «piills of Brooke’s 
rod. If pipe can not be had, a small chamber can be formed bj^ drilling, in which an 
indication of bottom may be obtained by coating the interior with white x>aint. 
THE BAR SOUNDING-ROD. 
In the absence of other material a serviceable sounding-rod maybe inij)rovised 
by taking two ineces of Hat bar-ii’on, from 1 inch to 1,^- inches wide and 2 feet long, 
and inserting between them three lilling xiieces cut from the same bar, x>lac,ed at 
irregular intervals as follows: One at the bottom, one 4 inches above it, and the other 
G inches below the detacher; drill or xninch corresxwnding holes through bars and 
lilling ])ieces and rivet them together; smooth the outer surfaces to insure free 
liassage through the hole in the sinker and adjust the detacher, the bars having been 
shaded for the i)urx5ose. The interior siiacc between the lower lilling i)ieces, being- 
coated with thick white iiaint, will serve as a specimen cu]>. 
LEADS AND OTHER WEIGHTS FOR SOUNDING. 
The time-honored lead, so familiar to all mariners as the medium of communi- 
cation between the surface and bottom by sounding, retains its place to a great extent 
in shoal Avater, and even in moderate depths, but has been sux)erseded for deexA sea 
work by modern axipliances. 
Hand leadSj weighing 7 to 14 xiounds, are used in shoal water and cast by one man. 
CoaHtimj leads vary in weight from 25 to 50 xiounds. They are used in dex>ths 
beyond the reach of the lighter hand lead, and usually when the vessel is under way; 
they are now frequently used in combination with wire and x>ueumatic sounders for 
navigational pui'x>oses, and dexiths of 50 to 100 fathoms are readily reached while the 
vessel is at full sx)eed. The general introduction of wire for deexi-sea sounding has 
increased its range and it is common x>ractice to use it in depths not exceeding 1,000 
fathoms where large bottt)m sxiecimens are not recxuired. A 35-xiound lead is used for 
this xBD'pose on board the AJhatrnss. 
Deep-sea leads range from 75 to 120 x»ounds in weight and are used for soundiug 
in moderate dex)ths, Avith rox>e; they are no longer in use on board vessels provided 
Avith wire for sounding. 
The au.riliary lead, weighing about 4 x)ounds, is attached to the stray line whenever 
wire is used in sounding to xHevent its kinking when the weight of sinker is suddenly 
removed by its striking the bottom. 
