Objects , Advantages, And Pleasures Of Science.

flight and path ; but there is a general resemblance between the course thoy take and the cycloid , Avhich has led ingenious men to adopt this opinion . If AVC have a certain quantity of any substance , a pound of wood , for example , and would fashion it in the shape to take

the least room , Ave must make a globe of it ; it Avill in this figure have tho smallest surface . But suppose wo want to form the pound of woocl , so that in moving through the air or water it shall moot Avith the least possible resistance ; then AVO must lengthen

it out for ever , till it becomes not only like a long pointed pin , but thinner and thinner , longer and longer , till it is quite a straight line , and has no perceptible breadth or thickness at all . If we would dispose of the given quantity of matter , so that it shall haA r e a certain length only , say a foot , and a certain breadth at the thickest part , say three inches , and move through the air

or water with the smallest possible resistance Avhich a body of those dimensions can meet , then Ave must form it into a figure of a peculiar kind , called the Solid of least resistance , because , of all tho shajies that can he given to the body , its length ancl breadth remaining the samethis is the one Avhich

, Avill make it move ivith the least resistance through the air or Avater or other fluid . A very difficult chain of mathematical reasoning , by means of the highest branches of algebra , leads to a knowledge of the curve , which , by revolving on its axis ,

makes a solid of this shape ., in the same Avay that a circle , by so revolving , makes a sphere or globe ; and the curve certainly resembles closely the face or head part of a fish . Nature , therefore , ( by which Ave ahvays mean the Divine Author of nature )

, has fashioned these fishes so , that , according to mathematical principles , they swim the most easily through the element they live and move in . *

Siqipose upon the face part of one of these fishes a small insect were bred endowed Avith faculties sufficient to reason upon its condition , and upon the motion of the fish it belonged to , but never to have discovered the Avhole size and shape of the face part ; it would certainly complain of

the form as clumsy , and fancy that it could have made the fish so as to move Avith less resistance . Yet if the whole shape were disclosed to it , and it could discover the principle on which that shape Avas preferred it Avould at once perceive , not onl y tlutt Avhat had seemed clumsy Avas skilfully

contrived , but that , if any other shape Avhatever had been taken , there Avould have been an error committed ; nay , that there must , nf necessity have been an error ; and that tho very best possible arrangement had been adopted . So it may be Avith Man in the

Universe , Avhere , seeing only a part of the great system , he fancies there is evil ; aud yet , if lie Avere permitted to survey the Avhole , Avhat had seemed imperfect might appear to be necessary for the general perfection , insomuch that any other

arrangement , even of that seemingly imperfect part , must needs have rendered the Avhole less perfect . The common objection is , that what seems evil might have been avoided ; but in the case of the fish ' s shape , it could not have been avoided . It is found by Optical inquiries , that the particles or rays of light , in passing through transparent substances of a certain form ,

are bent to a point where they make an image or picture of the shining bodies they come from , or of the dark bodies they are reflected from . Thus , if a pair of spectacles be held between a candle ancl the Avail , they make two images of the candle upon it ; and if thoy be held between the Avinclow

and a sheet of paper when tho sun is shining , they make a picture on the paper of tho houses , trees , fields , sky and clouds . The eye is found to be composed of several natural magnifiers Avhich make a picture on a membrane at the back of itand from this

, membrane there goes a nerve to the brain , conveying the impression of the picture , by means of Avhich Ave see . Now , Avhite light Avas discovered by Newton to consist of differently-coloured parts , Avhich are differently bent in passing through

transparent substances , so that the lig hts of several colours come to a point at different distances , ancl thus create an indistinct image at any one distance . This Avas long found to make our telescopes imperfect , insomuch that it became necessary to make them of reflectors or mirrors , and not of magnifying glasses , the same difference not being observed to affect the reflection ot