108 



BRITISH BIRDS. 



[vol. XIV, 



fairl}^ be termed " regular," whilst the remaining two show 

 considerable variation. The figures represent the time in 

 seconds — those in brackets the intervals on the surface : 



20 (5) 23 (4) 20 (6) 22 (5) 



(14) 28 (19)27(13)28(12) 



19. 

 26 



Buff el-head . . 15 (8) 20 (7) 20 (8) 

 Scaup . . 27 (11) 25 (11) 29 



(13) 25. 

 Harlequin . . 14 (15) 20 (15) 18 (18) 19 (15) 20 (15) 13 (12) 24 



(16) 20 (14) 20 (16) 20 10) 21 (15) 19 



Surf-Scoter . . 32 (14) 22 (12) 28 (16) 19 (18) 28 (18) 30. 



Buffel-head . . 12 (9) 19 (9) 26 (9) 3 (8) 22 (13) 20 (5) 24 (11) 

 28 (4) 27 (6) 22. 



From the above and many similar figures, which lack of space 

 forbids me to quote, it would appear not only that the intervals 

 between the dives are always much more regular than the 

 periods of submersion, but that the length of the interval has, 

 presumably, no bearing on the period of the succeeding dive. 

 It is true that my record for a Goldeneye — 55 seconds in one 

 fathom — out of 170 dives, was preceded by the unusually 

 long interval of 45 seconds ; but on comparing this with 

 other records, I believe such an interval, in this case, to have 

 been merely accidental. 



The length of the interval is nearly always shorter than the 

 period of the dive^usually about one half to two-thirds of it 



Table Showing Relation of Depth to Period of Dive. 



