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Union, namely, first, it has proved to ocular the chamber, which retina is a screen formed by demonstration the immense and varied unde- the outspread fibers of the nerve that comes in veloped resources of the South; and second, by from the brain. But while there is here a disthe interchange of ideas, opinions, and courte- tinct analogy between the eye and the camera sies between intelligent and reflecting men of obscura, there are differences which are curiboth sections which it afforded, the men of the ous and important. In the photographer's inNorth and of the South have learned to esteemn strument the rays are brought together on a each other more, to see the fallacy of the de- flat surface, and no combination of lenses has preciative representations by unscrupulous pol- yet been contrived to overcome completely the iticians on both sides, by which they were disadvantage of sharply defined details in the respectively misled and estranged, and by dis- center, shading off into indistinctness about sipating the prejudices which made Georgia a the edges of the picture. The maximum angle terra incognita to the citizen of Massachusetts, subtended by the field within which a toleraand Maine a remote foreign country, to the bly clear image can be obtained is forty-four citizen of Georgia, to promote social and com- degrees, while in the eye, owing to the concave mercial intercourse between them, and finally surface on which the rays are received, a field exert a good influence in shaping the policy of of one hundred and sixty degrees is obtained. the Federal Government.
The vision is not sharp over all this area, owing The financial result of the enterprise may to the constitution and distribution of the nervebe stated in round numbers as follows: fibers of the retina. In fact, the area of clearest Cost of buildings, etc...
$160,000 sight is very restricted, but the relatively large Kunning expenses....
100,000 surrounding surface of inferior sensitiveness Total...
serves the purpose of giving notice of the presSubscriptions..
$120,000 ence of objects in a wide field of vision, and Entry-fees, gate-receipts, etc
185,000 Sale of buildings....
guiding the eye to a closer scrutiny of them by 25,000
280,000 means of its wonderful facility of movement. Leaving for distribution to stockholders........ $20,000 eye from the brain and constitutes the channel
The optic nerve, which enters the back of the When all the accounts are paid, it is not im- of visual impressions, is a white cord nearly probable that this apparent surplus will be one sixth of an inch in diameter, and is comreduced to zero. As none of the stockholders posed of fine threads, at least 250,000 in numexpected any return when they subscribed, and ber. These spread out to form the retina, as they contributed with a view only to pro- which is rather a mosaic pavement than a true mote the success of a “World's Fair" at the net-work. The ends of some of the threads South, the number of dollars to be returned to turn back upon themselves and form relatively them is not a matter of any moment.
thick cones of nerve-matter, while others terThe buildings have been purchased for $25,- minate abruptly in rod-like ends. These are 000 by a stock company, who have also bought distributed somewhat irregularly, being closethe land from the city of Atlanta for $15,000, set only at one central point directly back of with a view to establish immediately a cotton- the pupil. This is the one spot of supreme senmill with not less than ten thousand spindles, sibility, and, being slightly depressed, is called with capacity of increase to twenty thousand, the forea centralis, or central pit of the retina. and with looms sufficient to weave the yarn It is constituted entirely of the cone-like terfrom all the spindles employed. The name of minations of the nerve-threads, relatively small the factory is to be the "Exposition Cotton in size and closely packed together, while Mills,"
around it is a less compact arrangement of the EYE-SIGHT, its DEFECTS AND TREATMENT. cone-like and rod-like terminations. Hence the In no branch of practical science has there visual picture is defined with consummate clearbeen greater advance in recent years than in ness only at this point, and presents a departthat which pertains to the structure and func- ure from the camera in the shape of an intensitions of the human eye. Perhaps the most fication of its chief defect, which in the eye thus important conclusions lately reached are those becomes a part of its exquisite perfection, for which have definitely determined the method the large area upon which the light falls affords by which the vision is adapted to near and a wide
field of impression sufficiently sensitive remote objects, and have ascertained the best to give notice of the presence of the objects means of preserving this power and of rectify- which are reflected upon it, while the fine ing its deficiencies. The similitude of the eye mechanism by which the eye is moved with a to the camera of the photographer is quite fa- facility, quickness, and accuracy that are marmiliar. It is well known that the rays of light velous, brings the slight area of perfect vision proceeding from external objects enter the to bear upon the
particular object to be scrutieye through the cornea or projecting horny nized or the different parts of that which is substance in front, pass through the pupil
, or merely looked at. Therefore, we have practiopening in the iris, into the dark chamber of cally combined perfect distinctness of the visthe eyeball, and are there brought together by nal picture and a wide field for its reception. means of a lens so as to form an inverted pict- The camera fixes its glance upon a narrow field, ure of the object on the retina at the back of and forms a picture with a clear center and
obscure or blurred outskirts. The eye sweeps on the retina. Connected with these elastic its glance over a wide range, and forms clear bands is a series of muscular fibers acting pictures of every part of the field in such rapid antagonistically to their elasticity; that is, succession as to receive the impression as a when the muscles contract, the bands relax and whole. This effect is, no doubt, promoted by allow the lens to bulge to a greater convexity, the curious anomaly that, while the vibrations it having a natural tendency to do so when not of light pass through a distance of 200,000 miles stretched out. When the muscular fibers are in a second, the nerve-influence passes from the brought into action so as to increase the coneye to the brain at the comparatively sluggish vexity of the lens, the vision is adapted to near rate of only two hundred feet in a second. objects; and it is the constant play of the elas
But the most important difference between tic bands and muscular fibers, together with the eye and the camera, and one that has only the ready movement of the eye, that adapts the recently been fully understood, is to be found sight to objects at all ranges of distance and diin the ineans employed for adjusting the instru- rection. The expansion and contraction of the ment to the reception of light from near and iris, so as to admit more or less light at once, remote objects. The lenses of the camera have add effectiveness to the marvelous contrivance each a constant focal length; that is, they bring by which the impressions of the external world parallel rays together at a certain distance from are conveyed to the brain. It is manifest that their own plane. If the rays are divergent the eye must be in constant action during the when received, a part of the power of the lens hours of wakefulness, and that its delicate is used up in bringing them parallel, and it mechanism is subjected to a strain from which must be farther from the screen, in order to the only absolute rest is sleep or complete concentrate the image distinctly upon it. So, darkness. if they are partly converged already, the lens These conclusions regarding the method by must be nearer the screen. Hence, by moving which the power of vision is adjusted to vari. the lens forward or back, the adjustment to ous distances have been thoroughly established near or distant objects is made. It was former- by the investigations of Sanson, Langenbeck, ly supposed that the eye had some such power Cramer, and Helmboltz, and are adopted by R. of elongating and compressing itself along the Brudenell Carter, one of the latest authorities axis of vision, but this has been entirely dis- on eye-sight. Professor Helmholtz has conproved. Its mode of adjustment is entirely trived an instrument for observing and measurdifferent. The eyeball is a sphere kept in ing the various curvatures of the crystalline shape by the fluids contained within its strong lens, which is turned to practical account in walls. These fluids serve a further purpose, producing optical compensations for defective not completely understood, in connection with sight. This perfected knowledge of the structthe lens, in refracting the rays of light, but the ure of the eye has in fact had an important lens alone contains the power of adjustment effect upon the treatment of defective vision. to distances. It is well established that there The crystalline lens is constructed out of a is a constant adjustment of the power of vision series of flattened fibers of albuminous subto the distance of objects. When the sight is stance, grouped in symmetrical loops around fixed upon near objects, distant ones in the six separate axes, and connected together at same direction can not be distinctly seen, and their edges by interlocking teeth. The transvice versa. Donders, the Dutch physiologist, parent mass is soft and pliable in youth, but it furnishes a simple but effective illustration of gradually grows denser with advancing years. this peculiarity of eye-sight. If a net is held This interferes with the facility with which it between the eyes and a printed page, the at- can be adapted to near vision, and is the cause tention may be fixed on either the net or the of failing eye-sight. In early life the lens can page, and either can be distinctly seen, but not be curved easily so as to bring objects not both at once. The attention may be rapidly more than four and a half inches from the eye transferred from one to the other, and the proc- clearly into view, but at the age of forty it ess of adjustment will follow it. The change can not form a clear picture of objects nearer which takes place is wholly in the form of the than nine inches. At fifty the point of nearest crystalline lens, not in its position or the shape sight is removed to thirteen inches, at sixty to of the eye. This lens is suspended back of the twenty-six inches, and usually at seventy all iris and between the aqueous and vitreous hu- power of accommodation is practically gone. mors. It is contained in a sort of sheath or The lens retains the uniform contour adapted shell of a slightly horny texture, which is set to distant objects, while it transmits the light in a circular rim. This rim is stretched out with a somewhat impaired degree of perfecin all directions and held firmly in place by tion. The remedy for this is to supply the seventy radiating elastic bands. These bands needed power of refraction by artificial lenses are about one fifth of an inch in length, and placed before the eye. By this means the are attached at their extremities to the outer power of clear vision for a certain fixed but coat of the eye. They stretch the lens to its convenient minimum of distance is completely fullest circumference, maintaining a certain flat- restored. The artificial lenses should vary in ness which adapts it to the light from distant convexity according to the needs of the eye. objects, so as to bring it to a perfect focus Mr. Brudenell Carter dwells with considerable
emphasis in his recent work on “Eye-sight, or it may be accelerated, and very often nearGood and Bad," on the inexpediency of post- sightedness originates in later life. It is most poning the use of artificial aids when they are prevalent where civilization is farthest adneeded. The failing of sight for near objects vanced, is more common in old than in new is the result of a loss of adjustability in the communities, in cities than in the country, crystalline lens which can never be regained, among brain-workers and cultivated people and the loss will be accelerated by overstrain- than among laborers and the illiterate. There ing the eye. Spectacles should be resorted to is a general agreement among authorities that as soon as they are needed, and should be a great development or increase of it takes always carefully adjusted to the actual need. place during school-life, and the result is largely Mr. Carter says: “It can not be too generally due to preventable causes. “There is no longer understood that spectacles, instead of being a any room for doubt," says Mr. Bradenell Carnuisance or an incumbrance, or an evidence of ter, “that badly-lighted and badly-fitted schools bad sight, are to the far-sighted a luxury be- form a great machinery for the development yond description, clearing outlines which were of myopia, and it is probable that this mabeginning to be shadowy, brightening colors chinery, where, as in Germany, it has for a which were beginning to fade, intensifying the long time been in unchecked operation, may light reflected from objects by permitting them have an important influence upon the form of to be brought closer to the eyes, and instantly the eyeball, which will be inherited by large restoring near vision to a point from which, numbers of the population.” Dr. Harlan defor ten or a dozen years previously, it had been clares that "it has been positively established slowly and imperceptibly, but steadily, de- by careful and extensive statistics that short clining. This return to juvenility of sight is sight is more frequently, if not almost excluone of the most agreeable experiences of mid- sively, developed during school - life.” Dr. dle age; and the proper principle, therefore, is Colin, of Breslau, reported, as the result of to recognize loss of near sight early, and to an examination of 10,000 school-children, that give optical help liberally, usually commencing 1,000 of them were near-sighted, and he found with lenses of 7 1.25 or + 1.50, so as to render that the defect increased numerically as the the muscles of accommodation not only able to pupil advanced through the different grades perform their tasks, but able to perform them of the schools. He found 67 per cent of myeasily. When, as will happen after a while in 'opia in the elementary, 10-3 in the intermeconsequence of the steady decline of accommo- diate, 19.7 in the high schools, and 26-2 in dation, yet more power is required, the glasses the gymnasia. Similar investigations with like may be strengthened by from half a dioptric to results have been made by Dr. Erismann, in a dioptric at a time, and the stronger glasses Russia, and by Drs. Agnew, Loring, and Lundy, should at first be taken into use by artificial in the United States. Dr. Lundy, of Detroit, light; the original pair, as long as they are found an increase of near-sightedness in a found sufficient for this purpose, being still twelve years' course at school from 0 at the worn in the day-time." Mr. Carter and Dr. beginning to 12 per cent in the highest grade, Harlan both strongly recommend, whether for a progressive development of 1 per cent a year. the failure of near vision or for near-sighted- Imperfect light, impure air, bad construction ness, the use of spectacles in preference to eye- and arrangement of desks and seats, and badly, glasses, which are less perfectly adjusted before printed books, are among the causes assigned. the eyes and less steadily held in place. Dr. Donders, of Utrecht, declares that the
Short sight is a defect of vision which arises foundation of near-sightedness is mainly laid from no natural or progressive modification of in schools, where, by imperfect light, the puthe organism of the eye, but it is often aggra- pils read bad print or write with pale ink." Fated and indeed produced by the bad condi- Another cause of injury to the eyes, as well as tions under which the eyes are used. The or- the general health, is the admission to schools, ganic cause of myopia is a too great depth of and too close confinement there, of children at the eyeball, which causes the sharp image of a too early age. an object to be formed in front of the retina There is a form of imperfect vision known instead of directly upon it. Eyes that are sub- as astigmatism, which is caused by a more or ject to this defect have a very sharp vision for less irregular curvature of the front part of the objects held quite close to them, but at a little eye. When it exists to any marked degree, distance the outlines become blurred and the vertical and horizontal lines can not be disdetails indistinct. The remedy is spectacles tinguished with equal clearness. It is in some with concave glasses, which should be adopted measure corrected by the use of glasses with a promptly when the need is discovered, because cylindrical instead of a spherical curvature. A by constant straining of the eye its defect will structural defect of the eye, in the treatment become aggravated, even if an actually diseased of which great progress has been made, is that condition is not induced. The organic pecul- known as cataract, in which the crystalline iarity which is the cause of near-sightedness is lens condenses and thickens until it becomes often inherited, and some children are myopic impermeable by light. It is now very effectu. at birth, but in general it is only the tendency ally treated by the complete removal of the that is congenital. This may be held in check, lens, the place of which is supplied by a
VOL. XXI.–18 A
properly adjusted lens of glass in front of the with opaque pigment. In the first weeks of eye. This, of course, is absolutely without the lite, moreover, infants are unable to shelter power of accommodation, and different glasses themselves from dazzling, light by changing have to be used for seeing at different dis- the position of the head.” Protection from tances. Professor Helmholtz adopts the con- too strong light and from sudden or violent clusion that the perfection of the eye depends changes either of light or temperature, proper not upon the excellence of its construction as attention to cleanliness and ventilation, and an optical instrument, but upon the manner in the intelligent treatment of purulent ophthal'which it is used. The chromatic aberration mia when it shows itself, would in his opinion of its humors, the astigmatism of its irregular prevent a very large proportion of the cases of contours, the blind-gaps of its nerve-screen, blindness generally believed to be congenital. the imperfect transparency of its refractive Artificial illumination is more trying to the media, the interposition of blood vessels in eyes than daylight, but, when its use is necesfront of the retinal membrane, the narrow limi- sary, the risk of injury may be reduced to a tation of the area of sharp definition, and the minimum. There is little choice between oilprevalent blurring of the lateral parts of the and gas-light of a similar illuininating power. field, are all conditions that must be classed as Mr. Carter remarks, “The best illumination optical imperfections. Yet every one of these for all purposes of close work is that of a imperfections is so counteracted and neutral- Silber Argand burner, it matters not whether ized in the use of the organ under the plan of for gas or oil, placed to the left front of the the employment of two eyes, and under the worker, a little above the level of the eyes, expedient of the rapid transference of the at- fitted with a shade to reflect light upon the tention to different parts of the image, that it table and to intercept it above, and with the is actually unrecognized as a defect, and undis- addition of an alum_ screen when the heat covered until the most refined powers of scien- is objectionable.” When several lights are tific investigation have been brought to bear used, they should be grouped together, as all for its detection.
cross-lights are distressing to the eye. Mr. There are many injuries to which the eye is Carter recommends that the least exacting subject, and many conditions having an impor- kind of work should be done in the evening or tant bearing on the preservation of good eye- at night; and, for literary men, reading and sight, besides those mentioned in connection study
by day and writing at night is the best with structural or induced defects of form. It arrangement. Reading in cars or other movis Mr. Carter's belief that a very large propor- ing conveyances, and the close use of the eyes tion of what is generally regarded as congeni- by dim or unsteady light, are universally contal blindness is really caused after birth by demned. Smoke is injurious to the eyes and ignorant or careless treatment. He puts the eyelids, but, aside from its external irritating proportion as high as ninety-nine cases in one effect, Mr. Carter does not agree with some hundred. The eyes of new-born infants are older writers in the opinion that tobaccodoubtless extremely sensitive to the effects of smoking produces any material injury to the light and temperature, and are imperfect!y eyes or optic nerves. According to the same shielded by nature. “From the imperfect de- authority, colored glasses should not be used velopment of the bones of the infant skull," except under competent surgical advice. But says Mr. Carter, " the eyes are placed, so to where protection is desired for healthy eyes speak, on the surface, instead of being in hol- from the glare of a strong light, or from refleclows; the eyebrows and eyelashes are short, tion on snow or water, pale cobalt-blue or thin, and pale; the eyelids are almost trans- neutral gray is to be preferred to green or parent, and the irides are imperfectly furnished very dark glasses.
F FALKLAND ISLANDS. These islands tance. No other English colony has relatively form & group in the South Atlantic Ocean, made such progress during the last ten years. about two hundred and fifty miles northeast of The population has doubled and the producTierra del Fuego. The number of islands is tion has quadrupled. According to the stateabout two hundred, but only two of them are ments of the English colonial office, the imports, of any considerable size. Their whole super- which in 1867 amounted to £20,590, had in ficies is reckoned at 5,000,000 acres. A few 1878 increased to £35,040. The exports, years ago penguins and sea-lions chiefly occu- amounting in 1867 to £15,460, had increased in pied their shores; but of late the English 1878 to £55,470. The population in 1867 was Government has encouraged emigration to 705, and in 1878 it had increased to 1,394. them, and now numberless sheep fatten on The value of the exports relatively to the numtheir grass. These yield to their owners such ber of the inhabitants is £40 to each; while in an abundance of wool that it has become an Australia it is £19 to each, and in the United article of exportation growing yearly in impor- States it is £4. The balance of trade in favor
of the colony is equivalent to £15 for each in- of fertilizers is rapidly increasing toward the habitant.
Mississippi Valley, and through Michigan, InFERTILIZERS. The system of agriculture diana, and Kentucky. The consumption in which consists in removing crops without re- the Atlantic and Middle States is estimated at storing the plant-food they take from the soil, not less than 500,000 tons, or about $20,000,000 and which Liebig aptly called Raubbau (rob- worth. Thousands of farmers, therefore, must bery-culture), has already reduced the soil of be using fertilizers successfully, else why this our older States to the condition where it must constantly increasing consumption? be fertilized or abandoned; where not only the The term commercial fertilizers properly apmost careful tillage, and husbanding of the plies to those articles occurring as natural demanurial resources of the farm, but also the im- posits, like guano and Chili saltpeter; or maportation of plant-food from outside, are req- nipulated in some way, like dried blood and uisite to the restoration of fertility. Guano, fish-scrap; or regularly manufactured, like suphosphates, potash salts, and the like, have perphosphates and potash salts, which are powbecome with us, as in Europe, indispensable to erful fertilizers, are expensive in comparison successful agriculture.
with farm manure, and are regularly quoted Every one of the Atlantic, and many of the in our market reports." Middle States, employ large quantities of com The history of the trade in commercial fermercial fertilizers. Their use is extending to tilizers dates back not more than about forty the prairies of Indiana and Illinois; and even years. The value of bone, fish, and even of in Kansas experiments are being made with superphosphate of lime, however, was recogthem on soil stated to be "worn out with nized long ago in farm practice.' "The tirst long cropping." Single towns in Connecticut settlers in this country learned of the aborigiare said to expend $20,000 per annum in arti- nes on the coast that a fish, planted in each ficial manures, and the State of Georgia im- hill of maize, greatly increased the crop; bones ports annually some $5,000,000 worth of plant- were used as manure in England, to some ex. food, in the form of phosphates, guano, potash tent, early in this century, and superphosphate salts, and the like, to restore fertility to her soils. of lime was made and applied by Sir James
The amounts of these materials sent out from Murray, in England, as early as 1817." the central markets in the spring of 1881 were In 1840 the first cargo of Peruvian guano so great as to make, in some places, a railroad was shipped to Europe. This date may be said blockade. The Commissioner of Immigration to mark the beginning of the use of commerof Georgia says: “It is frequently stated that cal fertilizers in agriculture. In the same the immense increase of the cotton-crop since year appeared Liebig's “Chemistry, in its Apthe war over that prior to 1860 is due to plications to Physiology and Agriculture," emancipation only. A most important factor which book, with his other contributions to in bringing this about has been the
very gen- the subject, made the beginning of that moveeral use of commercial fertilizers." The rapid ment which has created a science of agricultimprovement of Southern agriculture has been ure, and has enabled the art of agriculture to made practicable by various material agencies, meet the demands of modern life. of which this is one of the chief. Not freedom It is a not uninteresting coincidence that alone, but freedom and superphosphates, are two movements of such moment for agricultgiving us the “New South."
ure, artificial supply of plant-food to soils and How important a factor of the agricultural the rational application of science to their cultprogress of the country commercial fertilizers ure, should have received their first great imhave become is illustrated by the following petus at the same time. The ingredients to figures, partly official and partly general esti- which the efficacy of the more common commates, but doubtless reasonably correct: mercial fertilizers is mainly due are three-ni
The Commissioner of Agriculture of the trogen, phosphoric acid, and potash. Among State of Georgia reports that the number of the more important sources of these materials tons of commercial fertilizers inspected in that in the American markets may be mentioned: State in 1881 was 152,464, from which the - Nitrogen (ammonia).-The chief sources of State received $76,232 (a tax of fifty cents be- nitrogen are: nitrate of soda and sulphate of ing levied upon each ton consumed in Georgia). ammonia, which supply nitrogen without phos
Dr. Dabney, Director of the Agricultural phoric acid or potash; the various forms of Experiment Station of North Carolina, reports, slaughter-house refuse, dried blood, azotin, under date of December 15, 1881, that 50,000 tankings, etc., which contain nitrogen with tons were consumed in 1878, 60,000 tons in some phosphoric acid; and fish-scrap and Pe1879, and 80,000 tons in 1880; and that "the ruvian guano, which furnish both these ingresales this year (1881) will slightly exceed this dients in considerable quantities, the latter conlast amount."
taining also some potash. It is estimated that Virginia consumes over Phosphoric Acid.—The most important phos40,000 tons; Pennsylvania, over 50,000 tons; phatic materials are: bone-black, Canadian New Jersey, over 20,000 tons; New York, apatite, Navassa and Sonth Carolina phosover 35,000 tons; Ohio, over 15,000 tons; phates, and sundry "rock" or "washed" guaNew England, over 50,000 tons; and the use nos, as Curacoa and Orchilla, which supply