testing the different muscles. It is excellent for duction tests and for prism exercise.

The Hazen kratometer is a larger instrument on a table stand or clamp and makes use of prism batteries.

The phoro-optometers combine the Stevens' Phorometer with Maddox rod and Risley prism, and a trial frame for lenses, and forms the most complete prism test available. It may be had with either floor stand or with wall or chair bracket. A rack and pinion adjustment for height, and a spirit level permits fine adjustments, and makes it easy to determine when the instrument is level. The Risley prism is mounted in a swinging cell by which it can be moved to one side, and is provided with spring clips to indicate the proper position of the vertical and horizontal prism base, and prevents deviation during use. A multiple red Maddox rod which may be rotated in its cell is mounted so as to be swung aside when not required.

At the back of the instrument is a three-cell trial frame, the cylinder cell of which may be rotated by small wheels at the sides. Over the top is an adjustable forehead rest, no bridge being required. This trial frame accessory is provided with a screw adjustment for pupillary distance, and a scale to indicate it in millimeters.

In front of the instrument is a removable arm, which carries a sliding card holder for use in all near-point tests.

Another and later instrument combines with the one last described, a battery of spherical lenses mounted in disks. which may be rotated to give any spherical value by eighths of a diopter from minus 10 to plus 8; and in quarter diopters from minus 19.75 to plus 15.75. By adding a lense at the back a wider range may be had, if required. This instrument forms a complete trial case, except for cylinders, and the addition of a variable cross cylinder would make of it a

complete trial case. These phoro optometers may be had with two Risley prisms instead of only one, for use more particularly in prism exercise. The illustration shows the instrument equipped with extra Risley prism.

COMFORTABLE DISTANCE CORRECTION.

R. M. Lockwood, in the Optical Jaurnal and Review, calls attention to the fact that, although the accommodation and convergence are functions that are mainly the result of long mutual use and habit, still there is a certain strong inter-relation of the two which must be regarded if comfortable vision is to be given with glasses. When the eyes fix an object of regard, which means that there is single vision with consequent convergence, which is very exact as the visual centers strongly oppose diplopia, there comes an innervation to make the convergence just right, or a succession of innervations, each correcting the errors of the previous ones, and with these innervations to convergence there also comes a corresponding innervation of the ciliaries, which results in accommodation. Theoretically, the two functions should each be exactly correct, but practically this often does not happen; the convergence will be right, but the accommodation will be a little short, or a little over, the visual centers preferring to accept a slight blur of the retinal images rather than to make the extra effort to get a perfect image. In such cases the convergence and accommodation are not in harmony, but by the application of lenses of the right power and the right kind the two functions can be brought into harmony, when the vision will be the most comfortable attainable. The tests already made have settled the value of the cylinders, which is merely the measure of the difference in power of the two principal meridians of the eye; what we are to find is the

sphere which we must add to this to get the most comfortable vision, first for distance and then for near. To this end starting with the distance correction, leave in place the finding already gotten which is the cylinder selected and the static sphere; set the cross lines chart at oblique axes, put in front of the correction in the frame a cross cylinder plus .50 on a minus .50, which can be supplied by the optical houses mounted on a long handle, and make the axes of this cross cylinder exactly agree with the cross lines on the chart. The patient is to state which of the two shows the blackest and with the clearest edges between the black lines and the white interspaces. Should he say that the lines agreeing in direction with the plus axis of the cross cylinder are the best, then more plus must be added, which rarely happens; if he says the lines agreeing in direction with the minus axis of the cross cylinder are the best, then the minus spherical power must be added to the correction. To make sure the cross cylinder may be turned in the fingers so as to reverse the comparison with the test lines, when if there is a different result the average of the two observations can be taken. This test will give the sphere, instead of the static sphere previously found, which makes for the easiest vision, and should be the sphere prescribed in the first pair of glasses. The direction of the lines in the test do not necessarily have to be oblique as here stated; they may be set at any angle, the axes of the cross cylinders to be made to exactly agree, but as most eyes are unduly sensitive to the recognition of vertical lines, due to their long practice in reading print, it is better to avoid, as far as possible, the use of lines which are vertical or near thereto. In this test the cross cylinder used forms no part of the correction; it is simply the test lens to find the comfortable sphere. Its action is to blur one meridian myopically and the other hy

peropically to equal extents. This test is based on the idea that when we look at a chart with nothing but crossed lines on it we tend to accommodate for the distance of the chart, or for the chart as a whole, and when by the application of the right lenses we are exactly accommodated for that point which is also the point for which we converge, then the two lines or sets of lines will be seen equally clear, or rather equally unclear, for they are both blurred half a diopter; when this point is reached the two functions are in exact harmony. In this test the patient will usually note one set of lines as narrower than the others, but clearness of edges is the important point.

VISUAL REQUIREMENTS IN U. S.
ARMY.

"Vision, as determined by the official test-types, must not fall below 20/40 in. either eye, and not below 20/20 unless the defect is a simple refractive error not hyperopia, is not due to ocular disease, and is entirely corrected by proper glasses.

"In the record of all examinations, the acuity of vision without glasses, and also with glasses when the acuity is less than 20/20, will be given for each eye separately; in the latter case the correction will also be noted.

"Hyperopia requiring any spherical correction, anisometropia, squint or muscular insufficiency, if marked, are causes for rejection.

"Color-blindness, red, green or violet. is cause for rejection."

eye.

Enlisted men of the Ordinance, Subsistence and Quartermaster's Departments and for the Hospital Corps a minimum of 20/70 in each eye correctible to 20/40 with lenses, provided that no organic disease exists in either eye.

Recruits may be accepted for the line of the Army when unable with the better eye to recognize all of the letters on the 20/40 line, provided that they may be able to read some of the letters on the 20/30 line.

Circulars 4 and 5, 1908.

Reference to the "better eye" in the preceding requirements indicates the right eye, it having been determined that shooting from the left shoulder is undesirable.

Proposed Requirements. The proposed requirements which have been presented by the commission appointed by General Torney are as follows:

I. Requirements in the U. S. Military
Academy.

For Entrance.-A minimum of 6/6

Addenda.

Examination shall be made of the eyes of all cadets at the commencement of each academic year and if at any time during the course vision is found to have deteriorated to a degree greater than is required at graduation, the cadet shall be dropped. When a refraction error exists, cadets shall be commanded to wear the glasses prescribed for them. precisely as directed by the medical officer in charge.

II. Second Lieutenant from Civil Life. A minimum of 6/12 in one eye, and of 6/18 in the other, capable of correction in each to 6/6, and a normal color sense are requisite. The muscle error at 6 meters shall not exceed a hyperphoria of 2o, an exophoria of 5o, or an esophoria of 8°.

III. For Promotion.

For advancement through the various grades short of that of major, uncorrected vision must equal at least 6/24 in one eye and 6/30 in the other, and corrected vision, 6/6 in one eye and 6/12 in the other. For promotion to the rank of major and all higher grades no definite visual standard is required. The eyes, however, shall be carefully examined in each case, and if in the opinion of the Examining Board their condition. is such that they render the performance of the military duties peculiar to each rank impossible, the officer shall be recommended for retirement.

IV. Medical Corps. For Entrance.-A minimum of 6/18 is requisite in each eye, which is capable of improvement to 6/6.

For Promotion.-Uncorrected vision shall not fall below 6/30 in one eye and 6/60 in the other, and corrected vision shall equal 6/6 in one eye.

V. Hospital Corps.

For entrance and promotion, a minimum of 6/21 is requisite in either eye, which is capable of improvement to 6/6 in one eye and at least 6/12 in the other. VI. Enlisted Men of the Line of the Army and of the Engineer and Signal Corps.

A minimum of 6/12 for the better eye and of 6/30 for the poorer is requisite. VII. Enlisted Men of the Ordnance, Subsistence and Quartermaster's Departments and of the Hospital Corps.

A minimum of 6/21 for the better eye, and 6/30 for the poorer is requisite, correctible to 6/6 and 6/12, respectively.

Other Causes for Rejection. Apart from the visual standards which have just been described, and the restrictions as to muscle error and defects in the color-sense imposed in certain branches of the service, the presence of any structural changes or inflammatory conditions of the eyeball or its adnexa, such as might lead to impairment of vision later, are causes for rejection in all departments of the Army. Candidates whose eyes present merely the results of former inflammatory processes may be accepted, provided the eyes are entirely free from inflammation at the time of the examination, and that they possess the necessary degree of vision, and that the sequelae of the previous inflammation have entailed no serious impairment in the structure of the eye or its adnexa.

Directions for Carrying Out the Tests.

In testing the degree of visual acuity and of the balance of the extraocular muscle, the candidate must be seated exactly at 6 meters from the charts and the light used in the muscle test, and this distance must never be varied. (Six

meters shall be regarded as equivalent to 20 feet.)

For purposes of uniformity and to guard against the possibility of any deception on the part of the candidates, all tests shall be made with the standard charts issued by the department. These shall be exhibited to the candidate in a good natural or artificial light at a height of 4 or 5 feet from the ground. In the tests made at the Military Academy, the charts shall be illuminated by the Williams battery of electric globes, with daylight excluded from the room.

Each eye shall be tested separately and the examiner must exercise the greatest caution that the eye which is not under examination shall be properly excluded. During the performance of the test the lids must remain naturally open, squinting being prohibited. In the event that the candidate is unable to read all the letters on the line designated as his minimum vision, he will be passed, provided he is able to read three of the letters on the next smaller line with both eyes directed on the chart.

The manifest hypermetropia shall be detected by testing each eye separately, either by the so-called fogging system of first holding a + S. 3 D. or 4 D. lens before the eye and then gradually abstracting from its strength by holding S. lenses before it until 6/6 vision is attained, or by beginning with a + S. 0.25 D. and gradually increasing the strength of the lens until the letters on the 6/6 line are no longer visible.

The muscles of candidates at the Military Academy and of second lieutenants from civil life shall be tested with the Maddox rod, and a set of prisms. Their color-sense shall be ascertained by the tagged Holmgren worsted test of Williams.

L. Webster Fox,

GEORGE E. DE SCHWEINITZ,
MYLES STANDISHI,

WILLIAM CAMPBELL POSEY, Chairman.

D

WEIGHING THE BABY.

R. FRANCIS H. MacCARTHY gives in his recent book, the following valuable information as to growth and development of the child during the first year. "During the first three or four days of life, before the flow of milk becomes established, the infant usually loses from five to eight ounces. After nursing begins, however, this is soon regained, usually by the tenth day.

"From this time on through the first three months the infant should gain steadily from five to seven ounces a week. During the next three months the gain is slightly less, varying in different. children from three and one-half ounces to five ounces a week.

"From the sixth to the twelfth month the gain is about three and one-half ounces a week.

"The child with an average weight at birth of seven and one-half pounds would weigh at:

"It is interesting to note that a healthy baby will double its birth weight at five months, and at one year it will weigh almost three times as much as it did at birth.

"Babies fed from the bottle seldom gain as rapidly during the first month as infants fed at the breast, for the reason that it takes some weeks for the stomach to become accustomed to cow's milk, and during this time the milk must be weakened or the child's digestion will be disturbed. After this time, however, if the milk is prepared carefully, usually the gain will be about as regular as in nursing infants.

"While most healthy babies gain steadily during the first year, it should be remembered that there are certain times when no gain is made and the weight remains about the same. This may occur while the child has a slight cold or is cutting teeth, and sometimes during very hot weather.

"After the first year the gain in weight is not so continuous, and there are many interruptions which often occur without apparent cause. The weight and height of an infant must necessarily depend to some extent upon heredity and the conditions surrounding the mother before the baby is born. It is apparent, then, that no one rule or table of measurements will apply to all children, and that only average figures can be given.

"Table Showing Weight and Height of the Average Child.