682 THE POPULAR SCIENCE MONTHLY. 



bergs, and icebergs of enormous size, which, it is easy to avoid 

 except in the frequent fogs of the summer months. These ice- 

 bergs break from the immense glaciers bounding Melville Bay 

 and Kennedy Channel, which occasionally rise two hundred feet 

 above the water. It is apparent that the bergs breaking off irregu- 

 larly might, through a bulky form of the submerged part, attain 

 a still greater height. Hayes mentions a berg over three hundred 

 feet high in the "north water"; the Proteus on her last trip 

 sighted one a hundred and fifty feet high, six miles long, and a 

 little more than a mile wide. These immense bergs are most im- 

 portant agents in breaking up the ice-fields in early spring, for, 

 being propelled by deep under-currents, their motion is often con- 

 trary to that of the floe ice moved by the wind and surface currents. 



The wind also plays an important part, a southwest gale send- 

 ing the packs and hummocks upon the edge of the fast or land 

 ice, and crushing it for some distance, after which any northerly 

 wind disengages the free ice, leaving an open space, called the 

 inshore lead, which the earliest whalers always follow. It is, of 

 course, dangerous, as a south wind sends the pack back, and im- 

 prisons if it does not crush them. In July the quicker way 

 through " the middle passage " of the Melville Bay pack is used, 

 as the ice is then comparatively harmless, although vessels are 

 sometimes nipped and rather severely handled. 



No stronger vessels than those of the Dundee whalers are built ; 

 they are from four hundred to one thousand tons displacement, 

 have powerful, well-secured engines to resist the shock of ram- 

 ming or stoppage of the propeller by ice, and are built with an 

 eye to the easy and rapid replacement of rudder, propeller, and 

 propeller-shaft if damaged, these parts being carried in duplicate. 

 Above all other considerations, they possess strength for ramming 

 as well as resistance to lateral pressure when nipped. 



Another very important feature is that the bow shall have 

 considerable inclination, which permits the vessel, when ramming 

 very heavy ice, to lift slightly and slide on it, thus easing the 

 shock and assisting the cutting action of the bow with the down- 

 ward crushing weight of the ship. In this way it is possible for 

 these steamers at full speed to ram ice over twenty feet thick, and 

 receive no immediate incapacitating damage. 



If the ice is not too heavy, the shear -like rise and fall of the 

 bow is repeated several times as the vessel steams powerfully 

 ahead until her headway is checked. The difficulty then is to 

 extract the ship from the dock she has cut by her advance : the 

 floes press on her sides, cakes of ice and slush fill her wake, and 

 there is nothing but the ice-hampered propeller with which to 

 overcome her inertia and draw back out of the nip. Frequently 

 this is insufficient, and the ship may be crushed. 



