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Advantages of Studying the Mechanism of Animals. [Book III.

choked, the parts around them become diseased, like sterile land for wantof nourishment; does the pump itself stop working, we instantly die. Theregularity and irregularity of its motions are indicated by the pulse, whichhas always been adopted as the unerring criterion of health and disease,or as an engineer would say, the number of its strokes per minute, is theproof of its state wheth^r in good or bad working Order. The pulse notonly indicates incidental disorders in this hydraulic machine, but is a crite-rion of its age, as well as of its constant condition: the movements arestrong and uniform in youth, feeble and uncertain in sickness and age, andas the machine wears out and the period of its labor approaches, its strokesat last cease and its vibrations are then silent for ever.

What mechanic cän eontemplate this surprising machine without beingelectrified with astonishment that it should last so long as it does in somepeople ! Formed of materials so easily injured, and connected with tubesof the most delicate texture, whose ramifications are too complex to betraced, their numbers too great to be counted, and many of them too mi-nute to be perceived, and the orifices of all furnished with elaborate valves;that such complicated machi-nery should continue incessantly in motion,sixty, eighty, and a hundred years, not only without our aid, but in spiteof obstructions that are daily thrown in its way, is as inexplieable and mys-terious as the power that impels it.

Few classes of men are more interested in studying natural history, andparticularly the structure, habits, and movements of animals, than mechan-ics ; and none can reap a richer reward for the time and labor expendedupon it. It presents to the studious inquirer sources of mechanical com-binations and movements so varied, so perfect, so novel, and such as areadapted to every possible contingency, as to excite emotions of surprisethat they should have been so long neglected. There is no doubt thatseveral modern discoveries in pneumatics, hydraulics, hydrostatics, optics,mechanics, and even of chemistry, might have been anticipated by thestudy of this department of Science. Of this truth examples might be ad-duced from every art, and from every branch of engineering : the flexiblewater-mains (composed of iron tubes United by a species of ball and socketjoint) by which Watt conveyed fresh water under the river Clyde weresuggested by the mechanism of a lobster’s tail —the process of tunnelingby which Brunei has formed a passage under the Thames oecurred to himby witnessing the operations of the Teredo, a testaceous worin coveredwith a cylindrical shell, which eats its way through the hardest wood—and Smeaton, in seeking the form best adapted to impart stability to thelight-house on the Eddystone rocks , imitated the contour of the hole of atree. The fishermen’s boats of Europe , adapted to endure the roughestweather, are the very model of those formed for her progeny by the fe-male gnat; “ elevated and narrow at each end, and broad and depressedat the middle”—the beaver when building a dam—but it is vain to quoteexamples with which volumes. might be filled.