. Animal mechanism: a treatise on terrestrial and aërial locomotion. Animal locomotion; Flight. MOVEMENTS OF THP] WINGS OF BIRDS. 229 of each of which it is difficult to discover. There is therefore some limit to the precision of the measurements which we can take by the electric method; we can still, however, estimate by this means the duration of a movement with a tolerably accurate approximation. Myographic method.—We have seen that a dilatation accom- panies the contraction of the muscles, and follows it through all its phases. A shortening of the muscle, either rapid or slow, feeble or en
. Animal mechanism: a treatise on terrestrial and aërial locomotion. Animal locomotion; Flight. MOVEMENTS OF THP] WINGS OF BIRDS. 229 of each of which it is difficult to discover. There is therefore some limit to the precision of the measurements which we can take by the electric method; we can still, however, estimate by this means the duration of a movement with a tolerably accurate approximation. Myographic method.—We have seen that a dilatation accom- panies the contraction of the muscles, and follows it through all its phases. A shortening of the muscle, either rapid or slow, feeble or energetic, as the case,may be, will therefore be accompanied by a lateral dilatation which will have similar characters of rapidity or intensity. At each depression of the wing of a bird, the large pectoral muscles will be subject to a dilatation which it will be necessary to transmit to the re- gistering apparatus. We shall have recourse, for this purpose, to the apparatus which we have employed in determinations of the same kind, when treating of human locomotion. Some slight modifica- tions will enable them to give signals of the alternate phases of dilatation and relaxation of the large pectoral Fig 93.—Apparatus to investigate the contraction of the thoracic muscles of the bird. The upper convex surface is formed ot a membrane of india- rubber supported by a spiral spring; this part is applied to the muscles. The lower surface, in contact with the corset, carries four small hooks which are fastened in the stuff and keep the instrument in its place. The bird flies in a space fifteen metres square and eight metres high. The registering apparatus being placed in the centre of the room where the experiment is made, twelve metres of india-rubber tubing are sufficient to establish a constant communication between the bird and the apparatus. A sort of corset is fixed on a pigeon (see figure 94). Under this corset, between the stuff, which is tightly stretched, and. Pl
Size: 2254px × 1109px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectflight, bookyear1874
