The Swimming of Whales and a Discussion of Gray's Paradox

1. Whales swim by oscillating the tail and the flukes in a vertical plane. Tail and flukes move out of phase, the flukes leading on the tail by quarter of a wave-length. Photographic evidence is given and anatomical evidence referred to. Previous accounts of the movement are reviewed.

2. A theoretical treatment of the dynamics of swimming gives results in fair agreement with the only known observation of the frequency of tail-beat.

3. Support is given to Gray's suggestion that the drag of an actively swimming whale is less than that of a rigid model.

4. The possibility that whales develop more power (weight for weight) than man without going into oxygen debt is discussed. It is concluded to be unlikely.