of astigmatic artisans break down from inability to use their eyes in the calling they have chosen, on account of this peculiar defect, only thoroughly understood and properly corrected these last twenty-five years. To Professor Donders, of Utrecht, Holland, is the world again indebted for the practical solution of the trouble and the relief obtainable. Those directing our great industries where continued acute vision is necessary on the part of employes to make their industries pay, should give some heed to these arguments in behalf of their workmen, and urge rather than discountenance the testing the eyes, and wearing proper glasses.

The power of changing the focus of the eye, which is greatest at about ten years of age, changes, as I have said, and gradually decreases till at about forty-five or forty-eight, the necessary accommodation cannot be continued, and must be assisted by a convex glass. Now it is just at this time of life that an artisan is in the best physical condition to continue his skilled labor in which experience has perfected him. If the workman is near-sighted, then, although he will continue to need the same glasses for distance, he will need weaker and weaker ones for near objects, and finally be able to lay aside spectacles, except out-doors, Recall our friends whose faces we always associate with gold spectacles, and as they get on in life notice how they first push these gold frames up on the forehead at dinner, and afterwards in reading, and finally take them off, always, however, replacing them on the street, or in church, concert, etc. Only so far as all this goes, can a person be congratulated on being near-sighted; the other side of the picture I have already given.

Again, if the workman is over-sighted, with increasing years the glasses used for work must be stronger and stronger. The idea that this will go on till no glasses can be had strong enough is simply ridiculous, as there is only a certain definite amount of change, beyond which the alteration does not go, and which is far within even moderately strong glasses.

The perfectly normal eye needs glasses at forty-five to forty-eight years of age, just when the workman's experience is of value, and just when he is likely to have a family growing up dependent on him for support, just when also he cannot turn to any other work. To deprive him of their use would be to force him out of the artisan into the lower laboring class, fairly a cruelty.

In the female sex the refusal to wear glasses, and the various pretexts and concealments so well-known and recognized by the ophthalmic surgeon, are perhaps pardonable, because the admitting that they are fortyfive to forty-eight years of age is confessing that they are beyond the childbearing age-in other words, have "grown old." Curiously enough, one rarely, if ever, hears of a woman being threatened with loss of place or em→ ployment because she has come to need glasses. On the other hand, I cannot refrain from repeating that men who require the help of spectacles and who could work as well as ever with them, are only too frequently afraid to wear them for fear of loss of employment. The superintendent or the "boss" ignorantly supposes that the man's eyesight has given out, while on the contrary, if he has properly chosen glasses, it will be better than the few years before, when he has been striving to use his eyes, which he could not focus accurately, and. hence has produced imperfect or bungling work, which work has finally drawn the attention of the boss, who threatens

dismissal. The poor workman seeks aid and help at some special hospital, where he finds his sight is perfect with the right glasses there ordered for him after careful testing and examination. These he does not dare to wear in the shop, as the boss "don't want no man wearing spectacles." There is a most extraordinary ignorance and prejudice on this subject in the community, which it is the special purpose of this article to try and overcome. Now the workman has become skilled, steady with age and family ties, his vision will keep good till sixty-five or seventy, or beyond if he always has the proper helps to see. I ask, then, is there not money in retaining him, and should he,not be kindly urged and advised to wear what his eyes require? I am too familiar with all these facts not to know, and hence here insist that such foolish refusal to do what nature needs is one of the unnecessary causes of impaired vision.

SPECIAL CAUSES OF IMPAIRED VISION.

I have thus far been speaking of the natural conditions of the eye. I would now call attention to some undoubted causes of impaired vision connected with certain industries; in other words, the special diseases or injuries produced by them. There is as great a mistake in regarding as dangerous to the eyes occupations which are not so, as in considering as quite safe others which are hurtful. I would here point out some of the industries in which money can be made or saved by attention to points either not involving any expense, or but trifling in comparison with what is saved. A corporation treasurer told me that he once concluded to test at his mills whether all the doctors said about increased health and strength from perfect drainage had any truth in it. Accordingly, though all the drains aud sanitary points connected with the mill hands' houses would have passed muster from ordinary observers or masons, etc., he had the whole thoroughly overhauled, and each and every defect rectified. The cost was naturally considerabie, some thousands of dollars, and the money seemingly thrown away, till the superintendent in charge found the absence of the skilled hands from sickness was greatly reduced, and a careful estimate proved that the whole expense of repair of drainage, etc., was thus cleared in one year. How much greater was the gain in health, strength and happiness for the employes, benefited, perhaps, against their wills, as is so often the case!

Now, dust and dirt and foul air are the most potent causes in producing granular lids, the curse of many of the industrial classes, depriving them of months of labor if not of eyesight itself. Whilst we cannot tell the directors of our industries just how much they can save by eliminating dust, dirt, and foul air in their factories or works, we could perhaps excite their pity by showing them the effects of the same on the employes as they apply for help in our ophthalmic clinics and eye hospitals. In this article, however, no appeal is made to any feeling of humanity, but simply and directly to the pockets of stockholders, who may be induced to interest themselves, and direct superintendents and others to take cognizance of these things.

Years ago, the needle-grinders in England refused to wear the magnetic protectors over the nose and mouth, which relieved their work of any

special danger, because their wages were then reduced, and they preferred the money for a merry life and a short one, though they knew it would end in lingering pain. The time has, however, about passed for this sort of thing. Most artisans nowadays are alive to the value of their physical condition as affecting their power to labor, and hence their wages.

The waste of eye-power and positive injury to the organ from lack of attention to light, position of work, and illuminating sources, are more difficult to here render comprehensible to those who have the means in their hands of correcting abuses. An expert will hardly go through any establishment without seeing the apparently total disregard of the very points which would save eyesight, and render labor so much more comfortable, safer, and hence more profitable. How often do we see an artisan at work with an uncovered flickering gas-jet close to his eyes, when an almost costless piece of tin would protect them, and give him a better light! When, in another generation or two, we shall have become accustomed to a white, instead of a yellow, artificial light, there will be saved one great cause of impure air, inadequate light and hurtful heat. This latter is often wholly overlooked in the too close proximity of all lights, student-lamps, and gas-jets, to the head as well as eyes. Let those who doubt it test, even with the hand, the temperature of the head and brow on the side towards the light and the other in comparison. The simplest additional shade stops this, by making a current of air between itself and the lamp.

A little intelligent interest on the part of superintendents and bosses would often save the company the valuable services of those who give up their handiwork from defective vision just when their educated skill is of most value. Without any reason, work-benches, tables, etc., are often placed exactly as they should not be, simply from ignorance, carelessness, or prejudice. How often do we see artisans placed facing a window, the sun glaring in so as to cause most irritating reflection from their work before them! The strain on the eyes from the constantly-repeated act of accommodating or focalizing, as the man looks back from out the window to his work, is wholly unthought of till he breaks down under it, just at the age when he is of the most value to his employer, and his wages are most needed by his increasing family. A great many good men could be retained, and a good deal of money saved, by practical inspections and suggestions in our workshops and factories, provided, of course, that those in authority would heed the specialists' reports and act on them. At present the boss's reply to all this is, "It's the man's lookout, not ours, and we can easily supply his place." Setting aside all questions of humanity, this is not true. The loss of men with trained fingers, in a special work, is of great importance. No doubt the general deterioration of many kinds of fine work is due to the present lack of continued (for years) mechanical labor. Herein lies one of the elements of the success of foreign crafts. Of course this is by no means the whole cause of the "scamping."

The wear and tear on the eyes from the constant change of focus and accommodation, has been described to me by engravers, who, of course, did not know the cause of the trouble. They complained also of the loss of time before they could see distinctly as they turned from the picture to the

block, and that the first few lines then made were apt not to be good. All wood-cuts from photographs have to be worked over with loss of time and at expense of exactness. I do not speak without knowledge, and have the evidence of at least ten first-class engravers in this country.

I expect to excite the ire of those who are pecuniarily interested in photograph work. I have, however, no other interest than that of any physician in the patients who apply to him. Engravers are satisfied with my explanation of their not being able to endure this photograph work. I have confined myself to the strictly professional point of view, and not intruded any artistic ideas of others or of my own. On these points critics have recently expressed themselves strongly in the public prints.

I have dwelt on this subject of engraving from photographs, as well illustrating how certain forms of work are hurtful, and how the harm may be done from ignorance, and also not corrected or stopped from shortsighted mercenary motives, though it would pay better in the long-run to heed the warnings given. The artisan class have but little means of combining and resisting; thus those who have learned to be of value are thrown aside, from the ruling desire to get the golden eggs by cutting open the goose.

NOTE. In the Revue Scientifique for June 25, 1881, in which Dr. Javal's article is published, at p. 817, is the following:

"NEAR-SIGHTEDNESS IN THE SCHOOLS-On account of myopia becoming more and more frequent in the schools, from defective desks and seats, and bad lighting, etc., the minister of public instruction has appointed a commission on the hygiene of the sight in schools, with directions to examine the material conditions affecting the increase of myopia, and to endeavor to suggest means of avoiding them. This commission is composed of Drs. Gavaret, president, Panas, Gariel, Maurice Perrin, Javal; Mortmahon, inspector-general of primary instruction; Hachette and Masson, publishers; and Gauthier-Villars, printer."

VENTILATION.

BY JUSTIN M. HULL, M. D., MEMBER OF THE STATE BOARD OF HEALTH, AND CHAIRMAN OF THE STANDING COMMITTEE ON

VENTILATION AND HEATING.*

PURITY OF AIR.

In reply to the query, what is to be considered the standard of purity of air in dwellings? Dr. de Chaumont says: "We cannot demand that the air of an inhabited room shall be absolutely pure as the outside air. In every dwelling there will be some impurity of air. The quantity of air supplied to every inhabited room should be great enough to remove all sensible impurity, so that a person coming from the external air would per*Extract from the Second Biennial Report of the State Board of Health of the State of Iowa,

ceive no trace of odor, or difference between the room and the outside air in point of freshness. Following this is the amount of pure external air which should pass through the air of a room vitiated by respiration per head per hour."

To answer this, Dr. de Chaumont, as the result of numerous experiments says that per man, for each 100 cubic feet of space, 2,900 cubic feet of fresh air is required the first hour, and 3,000 cubic feet each hour thereafter. If a man is engaged in active work he should have more. If he weighs 150 pounds he should have from 4,500 to 8,600 of cubic feet of fresh air every hour.

Air is also vitiated by the combustion of coal gas. Walport estimates that for every cubic foot of gas 1,800 cubic feet of air must be supplied to dilute the product of combustion. A cubic foot of coal gas will produce nearly two cubic feet of carbonic acid. A common three-foot gas burner, burning four hours, will require 21,600 cubic feet of pure air.

NATURAL VENTILATION.

As to the methods of natural ventilation there are many devices. The air must be taken from a pure source. As a rule, says Parkes, "the inlet tubes should be short and so constructed as to be easily cleaned, otherwise dust lodges in them and the air becomes impure. They should be numerous and small, say from forty-eight to sixty inches superficial, so that the air may be properly distributed. They should be conical or trumpet shaped where they enter the room, as the air spreads out like a fan.

If placed above the heads of persons, they should turn upward, to lessen the risk of down draft. Externally, they should be protected from the wind by an overhanging hood or shelf. Valves may be placed in them to check too rapid change of air in cold weather. They should be distributed through a room so as to insure proper mixture of air. They should not be placed too near an outlet. If air cannot be warmed, it must not be admitted at the bottom of a room, but about nine or ten feet from the floor, and be directed toward the ceiling so that it may pass up and then fall and mix gradually with the air of the room.

Outlet Pipes.--The place for outlet pipes is one of important consideration. If there is no means of heating the air passing through them, they should be placed at the highest point of the room, enclosed as far as possible within walls, so as to prevent the air being cooled. They should be straight, with perfectly smooth internal surfaces so the friction may be reduced to the minimum. They may be round or square. They must be covered above by some apparatus (cowl, hexagon tube, etc.) which may aid the aspirating power of the tube and prevent the passage of rain into the shaft. The causes of downward draught in outlet tubes are, wind which forces down the air, rain gets in, evaporates and cools the air so it becomes heavier than the air in the room, or the air becomes too much cooled by passage through an exposed tube, so it cannot overcome the weight of the superincumbent atmosphere; or another outlet shaft with greater discharge may reverse the current.

Should down draught occur, flanges may be placed a little distant below the tubes so as to throw the air upward before it mixes with the air of the