8 
THE VOYAGE OF H.M.S. CHALLENGER. 
obtained. hen the tube is brought on board, the mud tube is unscrewed, any water 
that may be on the top of the mud cylinder is poured off, and the mud cylinder itself 
pushed out by a metal plunger, which just fits the tube. The water is simply poured 
out of the bottle into any convenient vessel. If the gases dissolved in the water are 
to be examined, then it must be drawn off by a 
siphon passed through the upper valve and down 
to the bottom of the tube. 
This sounding tube has been very successfully 
used on board the ships “Dacia” and “Inter- 
national,” belonging to the India-rubber, Gutta- 
percha, and Telegraph Works Company, while 
surveying the route for the cable from Cadiz to 
the Canary Islands. It has the advantage that on 
board such ships, where rapidity of work is of the 
greatest importance, good samples of mud and of 
bottom water are obtained in the course of the 
ordinary routine work, and without having to use 
any extra instruments. The weight of the sinkers 
used was 60 Ibs.,^ but 50 Ibs.^ is quite heavy 
enough. When the sinker is to be recovered, its 
weight should not exceed 30 Ibs.^ 
In some of the telegraph ships four small 
tubes were at one time fitted to the lower part of 
the sounding instrument, and brought up four little 
rolls of the deposit. Other slight modifications have 
been introduced in the form and size of the tube 
and valve for retaining a specimen of the deposit, 
but these do not differ widely from those which 
have been noticed above. 
Fio. 13.— The Beam-Trawl lued in <lecp-nca work. 
A water-bottle, called the slip water-hottle 
(Fig. 11), was almost always attached to the line 
when sounding on board the Challenger ; this bottle closes on .striking the bottom, and 
it frequently liappened that it was partly filled witli mud or ooze, thus giving, in 
addition to the sounding tube, indiaitions a.s to the nature of the deposit. 
In tlie drcd(jes and trawls (Figs. 12 and 13) used on board the Challenger, a large 
quantity of deposit was frequently brought up from the greatest depths of the ocean. 
' 27-2 kilfigramme*. * 22-7 kilogrammcH. ’ 13 6 kilogrammes. 
