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OLIVER: A Color-Sense Measure.

cylinders and prisms at O., and make the above apparatus serve in the ordinary examinations to take the place of the trial frames, thus saving the patient considerable delay and annoyance, as well as weariness, which comnes from wearing and rearranging the heavy frames.

A DESCRIPTION OF SOME MODIFICATIONS IN A COLOR-SENSE MEASURE. BY CHARLES A. OLIVER, M.D., PHILADELPHIA.

THE original form of the instrument is described in the December, I 88 I, number of the " Archives of Ophthalmology." Since then there have been some modifications in the working machinery and additions to the contrivance, of sufficient importance to allow a short description. The plate has been made of zinc, painted dead-black on its outer face. The slide

is composed of dead-black vulcanite, bevelled up on the sides; it runs up and down in two parallel bevelled flat brass rods that are firmly bolted to the back of the blackened disc. The order, number, and character of the colors upon the rotating cards have been chaniged. The first card has reflected red,

JACKSON: Refraction Ophthalmoscope.

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blue, and yellow situated upon it, with an equivalent open area, which when revolved into position, allows the second card to be brought into view: the second color-card contains reflected green, white, and transmitted red (made of a thin plate of gelatine), with an opening which corresponds to that in the first card; while a third card has similarly sized areas of transmitted blue, green, and yellow (composed of thin plates of gelatine, so arranged that new ones of any desired color can be substituted) contained upon it, with an opening similar to those upon the first and second cards. It will be thus seen that the modified Color-Sense Measure cannot be affected by variations in moisture and temperature, and that any number of colors can be employed by the use of bothi reflected and transmitted ligAht.

A NEW FORM OF REFRACTION OPHTHALMOSCOPE. BY EDWARD JACKSON, M.D., PHILADELPHIA.

THE proposal of another new form of refraction ophthalmoscope is probably not a subject for rejoicing; and, by those already skilled in the use of the excellent forms now common, is not likely to be regarded with any excess of favor. Undoubtedly a sufficient variety of forms is already in the market. Still, it must be admitted that heretofore the' highest ingenuity of ophthalmolkgists has been exercised mainly in devising elaborate, complete, and costly instruments, rather than in the attempt to furnish a simple instrument, of the greatest practical value and convenience, obtainable for a moderate expenditure of money. The instrument herewith exhibited is an attempt in this latter, less crowded, field of invention. It has been designed, not to enable the skilled ophthalmoscopist to measure accurately all possible errors of refraction, but rather to meet,

A Description of some Modifications in a Color-Sense Measure.

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