OF NATURAL HISTORY. 143 



It never was my intention, and, indeed, it would have 

 been foreign to tiie defign of this work, and ill fuited to that 

 clafs of mankind to whom I wifli chiefly to be ufclul, to en- 

 ter into the rationale of animal motion ; to mention the num- 

 ber, infertion, and direction, of the mufcles employed in 

 moving the different parts of animated bodies ; or to ac- 

 count for the modes by which animals walk, leap, fly, fwim, 

 creep, &c. Such difcuflions would not only require a 

 volume, but a thorough acquaintance with all the depths of 

 anatomical and mathematical knowledge. What follows, 

 therefore, will confift of lome defultory obfervations j and 

 the fubje£l fliall be concluded by enumerating a few exam- 

 ples of movements peculiar to certain animals. 



The motions of animals are proportioned to their weight 

 and fl:ru£lure. A flea can leap fome hundred times its own 

 length. Were an elephant, a camel, or a horfe, to leap in 

 the fame proportion, their weight would crufli them to 

 atoms. The fame remark is applicable to fpiders, worms, 

 and other infecls. The foftnefs of their texture, and the 

 comparative fmallnefs of their fpecific gravity, enable them 

 to fall with impunity from heights that would prove fatal to 

 larger and heavier animals. 



Motion gives birth, perfe£\ion, death, and reprodu6lion, 

 to all animal and vegetable beings. It is the caufe of all 

 that divernty and change which perpetually aiFefl every ob- 

 je£l in the univerfe. The globe we inhabit, as well as the 

 innumerable and ftupendous heavenly bodies which prefent 

 themfelves, in forms apparently minute to our obfervation, 

 confl:antly exhibit motions of the moft inconceivable rapidi- 

 ty. The magnitude of this earth, when coniidered with re- 

 lation to man, and other animals, appears to be exceedingly 

 great. It is indeed fufficiently fpacious, and fufiicicntly pro- 

 lific, for the conveniency and maintenance of its inhabitants. 

 The magnificent objects difplayed on its furface excite the 



