Xll LIST OF ILLUSTRATIONS. 



PAGE 



FIG. 24. Showing two successive positions of the arm of the instru- 

 ment, and the COTTespondiug positions of the tracing 



points of the levers 120 



FIG. 98. Elastic point, tracing on a piece of smoked glass . . 239 

 FIG. 102. Transmission of a to-and-fro movement by means of a 



simple traction thread 245 



ILLUSTRATIVE APPARATUS. 



FIG. 1. Showing the transformation of the electricity of a coil 



into mechanical work, heat, light, and chemical action . 10 

 FIG. 6. Appearance presented by the waves in a muscular fibre . 3G 

 FIG. 9. Transformation of heat into work by a strip of india- 

 rubber 39 



OF THE FLIGHT OF INSECTS. 



FIG. 84. Artificial representation of the movements of the insect's 



wing 199 



FIG. 85. Changes in the plane of the insect's wing . . . . 200 

 FIG. 87. Artilicial insect, to illustrate its flight .... 202 

 FIG. 88. Arrangement of the artificial insect, so as to obtain the 



hovering motion or the ascending flight . . . . 205 



OF TIIE HOVEUIKI; OF THE B.KD. 



FIG. 90. Instrument to illustrate the hovering of the bird . .217 

 FIG. 91. The same, explaining the upward turn . . . . 218 

 FIG. 92. ,, downward ditto . . .219 



ANATO.M Y. 



FIG. 13. Skeleton of a flamingo (after Alph. Millie-Edwards; the 



wing is very large, the sternum very short and deep, 

 which indicates the size and the shortness of the pectoral 

 muscles . . . . . . . . . . 72 



FlG. 14. Skeleton of a penguin: sternum very long, wing very 



short .......... 73 



FlO. 15. Ski h 'ton df the wing and sternum of the sea swallow 

 (Ilirundo marina); showing tin- extreme .short m->s of 

 the sternum, and the great length of the wing . . . 7t 



Fi<:. 89. Different curves in tin: wing of the liinl ait vaiions ji.i!^ ot 



its length . . 210 



FH;. 117. Active and passive parts of tho bird'i wing . . . . 'J7<> 



Flu. > S J. -Minetuiv n| th. in - t' \\ ing . . . . 1'Jb 



