HULLS OF VESSELS.--If some marine architect should come forward and assert that he intended to follow nature by making a boat with a hull of the shape or outline of a duck, or other swimming fowl, he would be laughed at, and justly so, because the lines of vessels which are most efficient are not made like those of a duck or other swimming creatures. MAN DOES NOT COPY NATURE.--Look about you, and see how many mechanical devices follow the forms laid down by nature, or in what respect man uses the types which nature provides in devising the many inventions which ingenuity has brought forth. PRINCIPLES ESSENTIAL, NOT FORMS.--It is essential that man shall follow nature's laws. He cannot evade the principles on which the operations of mechanism depend; but in doing so he has, in nearly every instance, departed from the form which nature has suggested, and made the machine irrespective of nature's type. Let us consider some of these striking differences to illustrate this fact. Originally pins were stuck upon a paper web by hand, and placed in rows, equidistant from each other. This necessitates the cooperative function of the fingers and the eye. An expert pin sticker could thus assemble from four to five thousand pins a day. The first mechanical pinsticker placed over 500,000 pins a day on the web, rejecting every bent or headless pin, and did the work with greater accuracy than it was possible to do it by hand. There was not the suggestion of an eye, or a finger in the entire machine, to show that nature furnished the type. NATURE NOT THE GUIDE AS TO FORMS.--Nature does not furnish a wheel in any of its mechanical expressions. If man followed nature's form in the building of the locomotive, it would move along on four legs like an elephant. Curiously enough, one of the first road wagons had "push legs,"--an instance where the mechanic tried to copy nature,--and failed. THE PROPELLER TYPE.--The well known propeller is a type of wheel which has no prototype in nature. It is maintained that the tail of a fish in its movement suggested the propeller, but the latter is a long departure from it. The Venetian rower, who stands at the stern, and with a long-bladed oar, fulcrumed to the boat's extremity, in making his graceful lateral oscillations, simulates the propelling motion of the tail in an absolutely perfect manner, but it is not a propeller, by any means comparable to the kind mounted on a shaft, and revoluble. How much more efficient are the spirally-formed blades of the propeller than any wing or fin movement, in air or sea. There is no comparison between the two forms in utility or value.