The morning journal-courier., 1908-12-02
EYES ARE VARIOUS
How Those of Men Differ from Those of Insects and
 Birds.
MATTER OF FOCUS
Interesting Facts as to the Use of the Vocal Organs Generally
 Unknown.

Mans eyes at rest are far focused will make no effort when seeing the moon or earthly horizons, Birds and fishes eyes at rest are near focused - win make no effort when looking at nearby worms and minnows Mans elastic lenses are under constant flat tening compression, says Harper's s Magazine. Imagine a rubber ball of flattened convex, lenslike shape, laid In between two disks of canvas, and the uniting edges of these cloths, stretched to a ring, They would flat ten the rubber, and if relaxed 1t would thcken by It's own elasticity. The thicker the lens the snorter its focus. For reading or threading q needle We relax the tension on the lens by con tracting a ring of muscle surrounding each lens and then wait for the lenses to thicken through their elasticity Tn fish the lense is set against the cornea Approximately, short focus, and when 1t wants to see whether tdc shadowy object some feet away is a | shark or a log, it pulls the entire round lensc toward the retina, and gets as clear a vision as possible. Now we see why so many human beings need "spectacles' as they grow old tho elasticity of tho lenses is gradual ly lost Just as 1t Is in rubber One more method of getting focus is em- ploycd by the eyemaker whicn Is dealt to some snakes Their lenses, which arc set near the retiuas, arc pushed forward, after the manner of a pumr piston, by blood pressure Cheap eyes for cheap creatures Focus regulated by excitement.
 Some of the "eycs that can sec ir the dark have no power of changing focus; so 1t makes no difference whether they get a night edition" o the days dolngs or not. There is z prevailing they say opinion tha birds sight is keoner tnan mans. ! This is probably not true, as only maI and the slmlae, which have "parallc vision" possess a highly concentrated sensitive area in the retnas-the ma cula lutea.
 But birds aloft are in clearer ali than man, and their eyes can chaug focus with remarkable speed, as nc cessitated by rapid flight Birds O prey have voluntary Subject to th
 wllD muscle, as well as involuntary in their Irdes. and can increase tn
 conveNlty of the cornea and its refrac
 tive power. Who has not wondore, how a sparrow-hawk could dar
 through brush and trees and neve turn a feather by collision? Man witt
 his flying machines will be in sor
 need of bird focusing speed.
 We can see the single eyes of som
 insects without lenso, as in the lo
 cust In viewing the house-Gy W need lens. The big, visible hulgin
 eyes we sec are composed of thou sands of unit conc-shapod eyes boln . into one compound eye each, or nor or less spherical shape. Under len they look like glass-eved payomer bent t, convexty Their facoted cor meas are variousy set in square, hexa gonal or prismatIC frames. Fac glistonng facet Is the cornea lens of distinct, self-working eye. Their nun Der in each compound eye is enc,
 nous, There arc 30 sucn eyeets each in the ant, 1,4O0 are allowed in drono bee, and $500 the workers our pet kitchen fly has 5000 chance Of seeing food crumbs, the beetle ovC
 5000, while more than 13O00 aid tr
 dragon-hy in his eleemosynary pursu
 of the mosquito, offset somewhat l
 several thousand awarded the latt,
 for a'"aporting chance' The haw
 moth gets pictures compounded l
 2o,oO0 contributors Over 25,0OO vii
 dow the brain of the mordella Cbeetlc
 and 60O00--so lt Is claimed--contru
 ute to the happy lives of some butte
 0ipg