Press enter after choosing selection

Facts In Natural History

Facts In Natural History image
Parent Issue
Public Domain
OCR Text

Probably you all know what is meant u y acycloid. If we maké a spot on a b leriphery of a wheel, travellngon a plain, a he figure which thí.t spot describes is a eyeloid. Nowjthere is no figure in which a body can be moved wiih so much veocity and such regularity of speed, not even a straight line. Mathemalicians discovered this not many years ogo ; but ! Nature's God taught t to ihe eagle 'ore mathemalics were invented ; and vhen the eagle pounces on his prey he a described the figure of a eyeloid. A globe placed in water or in air in moving ineets with resistnnee, and its ' ocity will be retarded. lfyou alter the B globe to the form of an eg, there will )e Iess resistance. And then there is a L form called the solid of least resistance, r vhicfi mathemnticians studied for many c vears to discover, and, when they had dis ' coveied it, they found tliey had the form of a fishes' ln'ad ! Naiure had % i! gedout' the fish with just such a l ure. The feathers of birds, and each 1 c ular part of them, are arranged at such ( angle as to be most efficiënt in assiating flight. The humnn eye has a mirror, on which these objects are reflected, and i a nerve by whicl these objects are conveyed to the brain, and thus we are enabled to tnl;e an interest in the objects which pass before the eye. Now, when the eye is too convex we use one knd of glasses to correct the fault ; and if be not convex enough, or if we wish to look at objects al a different distanc, we useg!a3es of entirely another description. But, as birds cannot get spectacles, Providence has given them a method of' supplying the deficiency. They have the power of contracting ihe eye, of making it more convex, so as to ee the speeks which float in ihe atmosphere, and catch thern for food ; and also of flatiening the eye, to see to a greaiordistance, and observe whether any vulture or othcr enemy is threatening to deslroy them. In addition to this, they have a film or coatings which can suddenly be thrown down over the eye to prolect it ; because at the velocity at which the? fly, and with the delicate texture of their eye the least speek of dust would act upon it ns a penknife thrust into the humai eye. This film is to protec! the eye, anc the same thing exists lo some extent in the eye of a ho'-se. The horse has a largeeye, very liable to take dust. This coating in the horse's eye, is called the huw, or thred eyelid, and if you will watch closely you may see it desceñe with electric velocity. It clears away the dust and protects the eye from injury. If the eye should catch cold, the haw hardens and projects, and ignorant persons cut itoff, and thus destroy this safeguard.You all know if you take a pound of iron andmake of ita rod a foot long, what weight it wil! support. But, if it be a liolloiv rod. it will support a weight many times greater than before. Nature seems to have taken advantage of this alo long before mathematicians had riiscovered it, and all the bones of animáis are hollow. The bones of birds are large, because ihey must bestrong to move their largs wings withsucli velocity ; but they must also be light inordei to floateasily on the air. Birds also Ilústrate another ftict in natural pbiíosóphy. If you take a bag, make it air tight, and put it under water, t will support a large weight, say anun dred pounds. But twist it, or diminish the air n it, it will support no such weight Now a bird has such an air bng. When he wishes to descend he compresses it and falis rapidly : when he would rise he ! increases it, and floats with ease. He also hos the power of forcing air into the hollow parts of the body, and thus to as ;sisthis flight. The same thing may b i obsorved in fishes. They also have a air bng to enable thcm lo rise or sink i ; the water till they find thcir proper tem pernlure.Il they wïsh to rise they íncrease it f they wish to sink thoy compress it, an down thoy go. Sometimos the fish i sinking makes too strongnn eíTort to compress his air Dag, and bursts it ; ihen down he goes to the bottom, and there rematas for the rest of his lile. Flounders and some other fish have no air bag, and so they are never found swimming on the surface, but most alwaysare caught on the bottom. ín this way are the principies of sciencs applied to nlmost every thing. You wish to know how to pack the greatest amount of matter in the smallest space. The forms of cyUndera laave largo open spaces between them. Mathematicians labored long to find what figure could be used so as to lose no space ; and at last fjund that it was the six-sided figure, and also that three planes ending in a ppint formcd the strongest roof or iloor. The honey bee discovered th same thing agreat while ago. Honey-comb is made up of six-sided figures, and the roof is built with three plane surfaces coming to