CHAPTEE I. 
ON THE VAEIOUS METHODS OF OBTAINING, EXAMINING, AND DESCRIBING 
DEEP-SEA DEPOSITS. 
a. Methods employed on board Ship. 
The various instruments employed on board ship for the purpose of obtaining infor- 
mation with reference to the deposits now forming on the floor of the ocean have 
been described in detail in the Narrative of the Cruise.^ In this place it is, however, 
proposed to refer briefly to these instruments with the view of pointing out the quantity 
of these deposits procured by the different methods, under various conditions as to 
depth, locality, and nature of the bottom. 
The ordinary deep-sea sounding lead, from 12 to 14 Ibs.^ in weight, armed with 
lard, often gives valuable and reliable information concerning the deposits in all depths 
under 100 fathoms.® This is especially the case where the bottom is hard, sandy, 
or rough, and if the lead be used frequently over a considerable area, and the particles be 
examined by the microscope after being freed from the grease by means of turpentine or 
naphtha. 
The Cup Lead (Fig. 1) is a modification of the ordinary deep-sea lead (A), with an 
iron spike (C) driven into its lower end ; at the bottom of this spike is an inverted hollow 
iron cone (B), and above the cone is a sliding iron disc (D) movable up and down the 
spike between the bottom of the lead and top of the cone, and just large enough to cover 
the opening of the cone when resting upon it. During the descent of the lead the 
disc is raised off the cone by the friction of the water, so that on reaching the bottom the 
cone is forced into the mud, and is filled with the mud or other loose material forming 
the deposit. On the lead being drawn up through the water, the friction of the water 
forces down the sliding disc (D) on the top of the cone (B), and thus prevents the 
contents from being washed out. 
The Valve Lead (Fig. 2) is another modification of the deep-sea lead, fitted at its 
base with an iron cylinder (A) having a common butterfly valve (B) at the bottom. 
This form of lead was found in practice to be the best for all ordinary soundings in 
depths under 300 fathoms.^ The cylinder being made to unscrew, the contents can be 
collected expeditiously, and usually without much loss. Even when the cylinder 
contained no specimen from the bottom, an examination of the lower edges would often 
1 Narr. Chall. Exp., vol. i. pp. 56 et seq. ^ 5‘5 to 6'4 kilogrammes. ® 183 metres. ■* 549 metres. 
(deep-sea deposits chall. exp. — 1890.) 1 
