Objects , Advantages, And Pleasures Of Science.

eye is hardly ever seen Avith anything upon it , though greatly exposed from its size and posture . The SAvift motion of the haw is given to it by a gristly , elastic substance , placed between the eyeball and the socket , ancl striking obliquelso as to drive out

y , the haAv Avith great velocity over the eye , and then let it come back as quickly . Ignorant persons , when this haw is inflamed from cold , and swells so as to aptpear , which it never does in a healthy state , often mistake it for an imperfectionand

, cut it off ; so nearly do ignorance and cruelty produce the same mischief . If any quantity of matter , as a pound of AA ' OOCI or iron , is fashioned into a rod of a certain length , say one foot , the rod Avill be strong in proportion to its thickness ; and

if the figure is the same , that thickness can only be increased by making it IIOIIOAV . Therefore , IIOIIOAV rods or tubes , of the same length and quantity of matter , have more strength than solid ones . This is a principle so Avell understood IIOAVthat

, engineers make their axles and other parts of machinery hollow , and therefore stronger with the same iveight , than they would be if thinner and solid . NOAV the bones of

animals are all more or less IIOIIOAV ; and are therefore stronger with the same iveight and quantity of matter than they otherwise Avould be . But birds have the largest bones in proportion to their weight ; their bones are more IIOIIOAV than those of

animals which do not fly ; ancl therefore they have the needful strength Avithout having to carry more weight than is absolutely necessary . Their quills derive strength from the same construction . They possess another peculiarity to help their flight . No other animals have any communication

between the air-vessels of their lungs and the IIOIIOAV parts of their bodies ; but birds have it , and by this means they can UOAV out theh bodies as we do a bladder , and thus become lighter Avhen they Avould either make their flight toAvards the ground

sloAver , or rise more swiftly , or float more easily in the air ; Avhile , by lessening their bulk and closing their Avings , they can drop more speedily if they Avish to chase or to escape . Pishes possess a poiver of the same kind , though not by the same means . They have air Wafers in their bodies , and can pull' them out , or press them closer , at pleasure ; AVIICU thoy ivant to rise in the

water , they fill out the bladder , and this lightens them ; when , they would s uit they squeeze the bladder , pressing the air into a smaller space , and this makes them heavier . If the bladder breaks , the fish remains at the bottom , and can be held up

only by the most laborious exertions of tho fins and tail . Accordingly , flat fish , as skaits and flounders , which have no airbladders , seldom rise from the bottom , but are found lying on banks in the sea , or at the bottom of rivers .

If you have a certain space , as a room , to fill up Avith closets or little cells , all of the same size and -shape , there are onl y three figures which Avill answer , and enable you to fill the room Avithout losing any space between the ceUs ; they must

either bo squares , or figures of three equal sides , or figures of six equal sides . With any other figures Avhatever , space Avould he lost between the cells . This is evident upon considering the matter ; and it is proved by mathematical reasoning . The

six-sided figure is by far the most convenient of those three shapes , because its corners are flatter , and any round body placed in it has therefore more space , loss

room being lost in the corners . This figure , too , is the strongest of the three ; any pressure from Avithout or from within will hurt it least , as it has something of the strength of an arch . A round figure Avould be still stronger , but then room would be lost between the circleswhereas

, with the six-sided figure none is lost , h' ow it is a most remarkable fact , that Bees build their cells exactly hi this shape , and thereby save both room and materials beyond Avhat they could save if they built in any other shape Avhatever . They build

in the very best possible shape for their purpose , which is to save all the room and all the Avax they can . So far as to the shape of the walls of each cell ; but the roof aud floor , or top and bottom , are built on equally true principles . It is proved the

by mathematicians , that , to give greatest strength , and save the most room , the roof and floor must be made of three square planes meeting in a point ; and they have further proved , by a demonstration belonging to the highest parts of Algebra , that there is one particular angle or inclination of those planes to each othes where they meet , Avhich makes a greater saving