Thank you for visiting SNEWPapers!
Sign up free
Literary
February 13, 1858
The Cecil Whig
Elkton, Cecil County, Maryland
What is this article about?
Explanatory passage on the wonderful mechanism in birds' eyes, describing the third eyelid (nictitating membrane) that cleans and protects the eye during flight, operated by muscles with a pulley-like system, illustrated by a string-and-stone analogy.
Clipping
OCR Quality
70%
Good
Full Text
Wonderful Mechanism in the Eyes of Birds
Singular provision is made for keeping the surface of the bird's eye clean -- for wiping the glass of the instrument as it were -- so for protecting it while rapidly flying through the air and through thickets, without endangering the sight. Birds are for these purposes furnished with a third eyelid, a fine transparent skin, which is constantly moved rapidly over the eyeball by two muscles seated in the back of the eye. One of these ends in a loop, the other in a string which goes through the loop, and is fixed in the corner of the membrane, to pull it backward and forward: If you wish to draw a thread or anything to any place with the least force you must pull directly in the line between the thing and the place: but if you wish to draw it as far as possible and with most convenience and do not regard the loss of force, you must pull it obliquely, by drawing it in two directions at once. Tie a string to a stone and draw it towards you with one hand and then make a loop on another string and, running the first through it, draw the one in one hand, not toward you, but sideways till both strings are stretched in a straight line: you will see how much more easily the stone moves quickly than it did before when pulled straight forward.
Brougham's Miscellanies.
Singular provision is made for keeping the surface of the bird's eye clean -- for wiping the glass of the instrument as it were -- so for protecting it while rapidly flying through the air and through thickets, without endangering the sight. Birds are for these purposes furnished with a third eyelid, a fine transparent skin, which is constantly moved rapidly over the eyeball by two muscles seated in the back of the eye. One of these ends in a loop, the other in a string which goes through the loop, and is fixed in the corner of the membrane, to pull it backward and forward: If you wish to draw a thread or anything to any place with the least force you must pull directly in the line between the thing and the place: but if you wish to draw it as far as possible and with most convenience and do not regard the loss of force, you must pull it obliquely, by drawing it in two directions at once. Tie a string to a stone and draw it towards you with one hand and then make a loop on another string and, running the first through it, draw the one in one hand, not toward you, but sideways till both strings are stretched in a straight line: you will see how much more easily the stone moves quickly than it did before when pulled straight forward.
Brougham's Miscellanies.
What sub-type of article is it?
Essay
What themes does it cover?
Nature
What keywords are associated?
Birds Eyes
Third Eyelid
Nictitating Membrane
Mechanism
Pulley System
String Analogy
What entities or persons were involved?
Brougham
Literary Details
Title
Wonderful Mechanism In The Eyes Of Birds
Author
Brougham
Subject
On The Mechanism Of Birds' Eyes
Key Lines
Singular Provision Is Made For Keeping The Surface Of The Bird's Eye Clean For Wiping The Glass Of The Instrument As It Were So For Protecting It While Rapidly Flying Through The Air And Through Thickets, Without Endangering The Sight.
Birds Are For These Purposes Furnished With A Third Eyelid, A Fine Transparent Skin, Which Is Constantly Moved Rapidly Over The Eyeball By Two Muscles Seated In The Back Of The Eye.
Tie A String To A Stone And Draw It Towards You With One Hand And Then Make A Loop On Another String And, Running The First Through It, Draw The One In One Hand, Not Toward You, But Sideways Till Both Strings Are Stretched In A Straight Line: You Will See How Much More Easily The Stone Moves Quickly Than It Did Before When Pulled Straight Forward.