APPEARANCE AT THE SURFACE 127 



immediately it split and the whales we pursued split up again, allowing themselves to be chased late 

 into the afternoon. Some seventeen hits only were scored. Had the animals been feeding, they would 

 not, presumably, have allowed themselves to be chased 20 miles from the site of their food and might 

 have been expected to show a certain indifference to the ship. The fact that they were not more ap- 

 proachable probably argues that they were not surfeited. Their gathering in such numbers at noon is 

 an unexplained incident. 



A similar concentration of about fifty whales was also met at 09.50 hr. on 27 December. Again, 

 their numbers split immediately on our arrival. The visibility was not good and at 13.00 hr., after 

 nineteen hits had been recorded, the original concentration was lost in mist. 



Sometimes whales indulge in superfluous splashing when in flight. On 13 or 14 December, a school 

 of maybe ten whales were chased at 11-12 knots. One or more of the leaders, whenever coming up 

 to blow, slapped the surface with its head, raising sheets of spray for yards to right and left. Similar 

 splashing has been noticed on other occasions, conspicuously in a Fin whale chased by the William 

 Scoresby on 24-25 January 193 1 : this whale was not sounding, however, and was running away at an 

 estimated speed of more than 12 knots. 



On 21 January a single Blue whale was consorting with four to five Fin whales (mark no. 7078). 

 The school fled, but periodically allowed the ship to overtake it and seemed to show some interest in 

 the ship ; in the course of an hour or two several were marked. The Blue whale detached itself from 

 the school and swam within a few feet of us. It took no notice of the firing, leaping high though not 

 clear of the water, now to the right and now to the left of the bows, and often within arm's length. 

 The antics could not have been watched at closer quarters, but the fading light and the quickness of 

 jumping made a detailed view of the movements impossible. 



Whales have not infrequently flicked a tail fluke out of the water in the final act of diving — a man- 

 nerism very similar to but apparently distinct from the kicking movement after being hit, for it has been 

 observed far from the ship. Certain whales were given to it more than others; some seemed prone to 

 lift the right fluke, others the left. 



Another eccentricity was shown by one whale on 22 December and by two whales on 7 January 

 which blew without showing the dorsal fin. 



Sei whales were always very difticuh of approach. They took more erratic courses than Fin whales 

 and kept well out of range ; when they reappeared after sounding they were usually far away and moving 

 in any but the direction in which the ship was heading. They were met with on few occasions. 



II. MOVEMENTS BENEATH THE SURFACE 



Various details in the movement of the whale as it breaks surface throw light upon the motions of the 

 body beneath the water, though the mechanical and hydro-dynamical principles underlying these 

 actions must at present remain undetermined. 



Breaking surface 

 Comparison of the slow, medium and fast methods of breaking surface suggest that the three 

 following relations are often found : 



(i) The degree of curvature of the body varies inversely with the period spent above water. 

 (ii) The depth of body showing above water also varies inversely with the period spent above water, 

 (iii) The period spent above water seems to vary inversely with the swimming velocity. 

 From these observations it may be argued that whales without momentum have some difficulty in 

 leaving the surface, and it may be noted that the respiratory process occupies but a small fraction of 



