262 CRUISE OF THE NEPTUNE 
wood planking. The timbers and planking in all are Very heavy, 
and the sides are further strengthened by a sheathing of green- 
heart or ironbark, both exceedingly hard, tough woods. This 
sheathing extends from above the water-line to near the keel; 
the planks forming it are from three to six inches thick, and 
are capable of resisting great pressure from the ice, as well as 
withstanding its cutting action which would soon wear through 
unprotected sides. The bows are further strengthened by being 
backed by several feet of solid timber, while, outside, thick 
plates and bands of iron protect the bow and stem. The sides 
are also strengthened by a layer of rock-salt, filled in between 
the timbers and between the skin of the ship, and by an inside 
sheathing fastened to the timber, so that with the outside 
sheathing of greenheart, the planking and the salt-filling, the 
sides are from eighteen to twenty-four inches thick. Notwith- 
standing this great strength, the usual fate of these ships is to 
be crushed in the ice. 
The ships are three-masted and barque rigged, differing in 
appearance from an ordinary wooden barque by the presence of 
large barrels fitted to the tops of the fore and main masts, and 
used for observation stations when working the ship through 
ice or when chasing whales. The small engine and boiler are 
placed aft, between the main and mizzen masts, where the 
strong deck beams can be best spared. The engine works a two- 
bladed propeller, which drives the ships at rates varying from 
four to seven knots an hour. 
The lower hold of the ship is filled with a number of iron 
tanks that rise to the level of the middle deck, and which are 
used to store the blubber. On leaving home all these tanks are 
filled with coal, which is also stowed in every other available 
space, the usual amount of coal for the voyage being from 250 
to 300 tons. The between-deck space is used for stowing provi- 
sions, and for the quarters of part of the crew. 
