20 
occupying the space of a wave of displacement, and so we 
have ships 9, 10, or even 11 times as long as broad and 
twenty times the length that they have draught. Now 
knowing as we do the magnitude of the skin resistance in 
ships and its smallness in the oily coats of fishes, one would 
expect that the length of the latter would be greater pro- 
portionally than that of the former, if ships were built in 
the proper form to secure a high velocity. But what is the 
fact ? — On an average of sixteen fresh water fish delineated 
in Daniell I find that the extreme length inclusive of the 
tail fin is 4*22 times that of the extreme depth exclusive of 
the dorsal and ventral fins. The average breadth will be 
perhaps J of the depth, making the proportion to length 
about 1 : 8. 
On an average of three species of Whale, the Narwal, 
Greenland Shark, Dolphin, and the Porpoise, I find from 
Scoresby and other authorities the proportion of either depth 
or breadth to length, to be about 1 to 4*7, they having nearly 
circular sections. Therefore it appears that while in ships 
the proportion of length to width of midship immersion is in 
ships as 5 : 1, that of the shark, the porpoise, or dolphin, is 
not more than 1 J : 1. 
Dr. Scoresby, in his e Arctic Regions,’ gives twelve 
miles per hour as the utmost speed of the Whale. But 
Mr. Baxendell gives it a velocity approaching 20 miles. 
I had an opportunity of witnessing the wonderful swimming 
powers of the porpoise during a voyage to the Clyde in the 
‘Owl’ steamer on the 29th June last. About 8 a.m., the 
sea being calm near the Mull of Galloway, we were beset 
by a shoal of these animals which raced with the ship and 
kept along side for 3 or 4 minutes with the greatest ease. 
They swam in twos and threes at a foot or two distant from 
one another, several approaching within ten feet of the 
vessel, which was steaming at the rate of 13*4 statute miles 
per hour. If such a velocity can be maintained by the 
