78 
WATER AND WATER NAVIGATION. 
can’t give up the balloon principle for water-flotation any 
more than fome others can’t give it up for air-flotation. 
And the former of thefe good people believe to-day as 
firmly in the pretty legend of the u fwim-bladder ” to 
float the fifh up through the waters as the latter do in 
“ heated air cells ” and “ hollow bones filled with air ” to 
make the birds light enough to fly! And yet there isn’t 
anything in nature to warrant one more than the other. 
Locomotion (including flotation) in the water is juft 
as purely a mechanical affair as locomotion in the air and 
on the land. 
And the hifiory of all water-animals proves what I 
fay. 1 
And if it requires no more motive-power to produce 
flotation than propulfion, why can we not employ the 
power of the Steam-Engine of Steamfhips to create Me¬ 
chanical Flotation and prevent the veflel from finking, no 
matter how leaky or how far diftant from land ? 
And fop making a graveyard of the Deep ! 
It ifn’t an agreeable fenfation to be on board a fteamer 
in mid ocean and have fomething happen. It makes you 
1 “ The otaria or fea-bear,” fays Pettigrew, “ fwims, or rather flies, under 
the water with remarkable addrefs, and with apparently equal eafe in an upward, 
downward, and horizontal direction, by mujcular efforts alone ! ” (The italics 
and exclamation are mine.) Pettigrew continues as follows : “ An obfervation 
which may likewife be made regarding a great number of fifhes ”—(why not 
all?) — c ‘ flnce the fwimming-bladder or float is in many entirely abfent! ” In 
confirmation he quotes the following from Owen : “ The air-bladder is wanting 
in the dermopteri, plagioftomi, and pleuronedlidas.”—Owen, op. cit., p. 255. 
