COMMON FINBACK WHALE. 193 



animal is exposed above water at a time. The characteristic positions of the shallow, surface 

 dives made as the whale comes up to breathe several times in succession, are to be distinguished 

 ' from those of the deep dive or 'sounding' made at the end of the series of shallow dives, 

 when the whale, having refreshed its lungs, plunges below for a longer stay. On again coming 

 to the surface from the depths, it rises obliquely, and at the moment the blowholes at the 

 vertex of the head, are exposed, the vaporous breath is expelled with great force to a height 

 which probably does not exceed fifteen or twenty feet (Andrews). The sound produced by 

 this rush of breath is audible at a considerable distance and is said to be sharper than the noise 

 made by the Humpback. The column of vapor is of characteristic shape, directed vertically 

 upward, narrow at first, expanding evenly to the summit, like a thin-stemmed vase, without 

 appearance of its double origin. As the cloud of vapor dissolves the inspiration takes place, 

 the widely expanded blowholes close, the head is depressed slightly and as the forward part 

 of the whale sinks under water, the top of the shoulders and back successively appear, until 

 the high dorsal fin comes clear out. By this time the front part of the body is already sink- 

 ing, and soon the ridge of the back and finally the dorsal fin disappear. The tail is not shown. 

 Several of these shallow dives follow, at somewhat regular intervals usually about six to ten 

 or twelve in succession. Andrews (1909) found that the Pacific Finback usually spouted 

 about four times at fifteen-second intervals before sounding for a longer period. In sounding, 

 the body is much more arched than in the shallow dives, and the whale goes down at a sharp 

 angle. In ordinary course the whale may appear again in from four to fifteen minutes or 

 longer (Andrews timed a Pacific Finback that was down for twenty-three minutes). It is 

 unknown what the maximum time may be that a Finback can remain under water, but proba- 

 bly it is not above half an hour. It often happens that whales sound and are not again seen. 

 No doubt in such cases they go a long distance and when next they rise to the surface, are too 

 far away to be easily made out. The appearance of the spout may be modified by the action 

 of the wind, or it may vary according to the force with which it is expelled and the amount 

 of moisture contained in it and the surrounding air. It is not altogether the colder tempera- 

 ture of the au- that causes the vapor to become visible through condensation, as in case of 

 our own breath in winter; for the spout is equally visible under the tropics. No doubt the 

 explanation, as first advanced by Racovitza (1903), is that the vapor becomes surcharged 

 with moisture under pressure in the whale's lungs, and when violently expelled, it expands. 

 This sudden expansion in accordance with a well known physical law, causes an immediate 

 lowering of temperature sufficient to produce momentary condensation of the water particles 

 contained, which therefore become visible as a 'spout.' It is strange how hard it is, never- 

 theless, to root out the idea that a whale spouts water engulfed through its mouth; and I 

 have even known persons of education to believe that it spouted oil, manufactured within its 

 blubber ! 



