Animal locomotion or walking, swimming, and flying - with a dissertation on aëronautics (1873) (14580891577)

Identifier: animallocomotion00pett (find matches)
Title: Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics
Year: 1873 (1870s)
Authors: Pettigrew, James Bell, 1834-1908
Subjects: Animal locomotion Physiology Aeronautics
Publisher: London : Henry S. King & Co.
Contributing Library: Yale University, Cushing/Whitney Medical Library
Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library



Text Appearing Before Image:
d mode of applying their travelling surfaces are takeninto account. If the aerial flying bird was lighter than the air,its wings would require to be twisted round to resemble the diving-wings of the penguin and auk. If, on the other hand, the diving-bird (penguin or auk) was heavier than the water, its wingswould require to resemble aerial wings, and they would requireto strike in an opposite direction to that in which they strikenormally. From this it follows that weight is necessary to thebird (as at present constructed) destined to navigate the air,and levity to that destined to navigate the water. If a birdwas made very large and very light, it is obvious that thediving force at its disposal would be inadequate to submergeit. If, again, it was made very small and very heavy, it isequally plain that it could not fly. Xature, however, has 94 ANIMAL LOCOMOTION. struck the just balance; she has made the diving bird, whichflies under the water, relatively much heavier than the bird lit
Text Appearing After Image:
- ci S2 :-■ > d 2 e §51 .... w§-?s c £ a .rf V £ ? -5 tc - - — rt 3 > c: > — —~~ ~~ +1^ ^cs .2 ^ 2 Z g, - ^S s rt 2 c o -2 -3 « 5 % * 5 -r - 4 g I :s S -*»«•§ 1 2.3 2 =3 SoJ ^.S^-s . s <u 2 s § — ~ - ^ ^ ® ! 2 J? ® o 3 81 r.rlc-l ill!o is 5 « 5 a SI which flies in the air, and has curtailed the travelling surfacesof the former, while she has increased those of the latter. PROGRESSION ON AND IN THE WATEB. 95 For the same reason, she has furnished the diving bird witha certain degree of buoyancy, and the flying bird with a cer-tain amount of weight—levity tending to bring the one tothe surface of the water, weight the other to the surface ofthe earth, which is the normal position of rest for both. Theaction of the subaquatic or diving wing of the king penguinis well seen at p. 94, fig. 47. From what has been stated it will be evident that thewing acts very differently in and out of the water; and thisis a point deserving of attention, the more espec