these occasions may induce the attending physician to apply many local applications, or to administer a great variety of remedies in the hope of appeasing; but such vacillation, though it may elicit sufficient commendation from the by-standers to fan the vanity of the doctor, can be of no service to the child. As the accomplished general about to enter a battle surveys the ground before marshalling his batallions, so the educated physician should carefully diagnose his case, fully decide upon the course of treatment, and modify it only as circumstances may require.

Ophthalmology and Otology.

THE STUDY OF THE OPHTHALMOSCOPE. By R. J. PEARE, M. D., House Surgeon, University Hospital, Ann Arbor. The difficulties encountered by every student in the practical study of the opthalmoscope are so great as to be probably the main cause for the general lack of knowledge which prevails on the subject of ophthalmic medicine. But few pages of any work on diseases of the eye can be read without being reminded of the frequent necessity of the opthalmoscope in diagnosis, and the cases are not numerous in which an examination can be considered complete without its assistance. A knowledge of these facts confronts the student at the outstart of his studies, and he endeavors to shape them accordingly. Having thoroughly studied the ophthalmoscope theoretically, he attempts its practical use, but finds after earnest and repeated effort that little or no progress is made. Becoming thoroughly disgusted, the opthalmoscope, and with it ophthalmic medicine, is laid aside, and those who talk of seeing arteries and veins, optic disc and yellow spot, of distinguishing between diseases of the different layers of the retina, of diagnosing glaucoma by the

condition of the optic disc, and many other such wonderful things, are thought to be drawing considerably upon their imagination, or to possess uncommon faculties which especially adapt them for their work. Now this is a wrong impression, for those who understand the instrument and can make practical use of it, have, as a rule, no special genius, but only excel somewhat in a higher quality, namely, perseverance.

Not a little may sometimes be done by those who have surmounted difficulties in levelling the way for others who may be following in the same path, and it is with this hope that the present article is written.

By comparison of the complex with the more simple of things which are fundamentally alike, study is frequently facilitated. In the present case this is possible. The ophthalmoscope belongs to a class of instruments called specula, which have but one thing in common, namely, the power to illuminate dark cavities and passages by reflected light. To this are added other contrivances which adapt the instrument to different purposes, and increase its usefulness. For study, three of the class will be sufficient, namely, the vaginal speculum, the otoscope and the ophthalmoscope, whose complexity increases in the order named. For vaginal examination, in addition to the reflection, some means of dilating the passage is required, the walls of the canal otherwise remaining in contact. A tube is used for this purpose, or some modification of a tube, the inner surface of which is made to reflect light strongly. The passage being dilatable, the instrument may be made of such calibre as to admit of enough diffuse light for all practical purposes; and the parts to be examined not being minute, the eye of the examiner need not approach so closely as to cast the shadow of the head upon the instrument. Though, no douubt, a concave mirror would add to the illuminating power of this speculum, yet as it would render its use more complicated without proportionately increasing its usefulness, this addition has not been made; and the vaginal speculum in its tubular form remains the most simple of its class,

and best illustrates the fundamental principal common to all. Now, to the vaginal speculum, (modified in size to suit the ear), if we make the addition of the reflecting disc we have an ear speculum or otoscope. The external meatus being surrounded by a bony wall is undilatable, and being small, sufficient diffuse light is not admitted for the close examination of parts which are minute. Moreover, the observers head, being in necessarily close proximity to the instrument, obstructs the light. The use of the disc reflector obviates these difficulties by reflecting concentrated light into the cavity and by enabling the observer to place his eye in the centre of the emerging rays. Thus, so far, we have the reflector as the essential thing in both these instruments, and, as auxiliary, the tube, which serves either to dilate or to straighten the passage, according to its design, and thus to facilitate the examination.

In the examination of the eye, though of all examinations the most difficult, we fall back to the elementary form of the speculum, namely, the reflector. Practically the tube is not here necessary, though virtually we are not without its assistance, for by the intraocular pressure the walls of the organ are kept in the most favorable condition for our purpose, which substitutes the use of the tube.

There is therefore really no essential difference between the ophthalmoscope and a vaginal or ear speculum. But in the specular examination of the eye we encounter the optic lens, which adds a feature to the case not before met with. But suppose that in the use of the other instruments we desire to increase the size of any object under observation, we have but to use such a lens as that of the eye, holding it at its focal distance from the object, and the resemblance is again restored. Now, any intelligent physician would be competent to make such an examination at a moment's notice, but when he makes the attempt upon the eye it is found a difficult matter; a new and very troublesome element has to be dealt with in the power of the lens to oscillate in its focal condition between the extremes of

the range of accommodation. What does common sense teach us to do in this case? It is very obvious that if the ocular lens can be placed in the same physical condition as the lens used as mentioned in the other examinations, we ought to encounter no greater difficulties, excepting those which arise from the unsteadiness of the eye while under the glare of the reflector, and the minuteness of the aperture through which the observer must look. To so arrange the patient's lens, he has but to look at some distant object in the room, in other words, to fully relax his accommodation. The lens being adjusted at its focal distance from the retina, the rays emanating from it will be parallel, which only requires that the observer's eye should be in the same condition to receive them, when the details of one retina will be transmitted to the other and be pictured upon it in an erect image.

Such are the general resemblances of all specula, indicating clearly that so far as they are alike their management is similar and equally easy, and that the difficulties in the use of the ophthalmoscope arise not from any peculiar complexity of the imstrument but from that of the organ for whose examination it is intended. These, as already mentioned are mainly the unsteadiness of the focal adjustment and the uneasiness of the eye and smallness of the pupil under the glare of light, and they can only be overcome by studying them carefully and acquiring expertness with reference to them, by repeated practice in the use of the ophthalmoscope. No more can we expect success in our first attempt at ophthalmoscopic examination than the child can in walking or the boy in swimming. Perseverance gives the only assurance of success, for earnest effort is seldom seen to go without a crown.

The following described little contrivance, which can be made in an hour without any expense, to one who already has an ophthalmoscope, will be found a most valuable aid to the study of that instrument, being in fact an artificial eye, whose parts are at our command and may be arranged in a variety of ways so as to produce all the conditions found in the eye, as nearly, at least,

as an artificial can resemble an organic structure. A cylinder of cardboard two inches long, and one and one-half in diameter is first to be made, and then two covers, one for each end of this. One cover must have a ring of one and onehalf inch in depth; the other one-half inch, so that when both are on the cylinder they will cover it completely. The shallow cover is to be used as the top; the other is the bottom of the instrument. In the top cover make a central aperture about the size of the natural pupil, and ream its edge with some polished substance till it is smooth and free from projecting fibres. In the top end of the cylinder, about one-eighth inch from the edge fasten a diaphragm, also perforated. This opening must be one inch in diameter. Now place some fine print in the bottom and a two-inch lens between the top and diaphragm and the instrument is complete and ready for use, in all respects as an eye would be in ophthalmoscopic examination. The depth of the rim of the bottom cover enables the student to adjust the instrument for lenses of different powers by drawing it out, and in the same manner to produce the condition which so puzzles the student when observing in the erect image an eye adjusted for some point short of infinity. The lens, being adjusted for a point beyond its focal distance from the print, the rays diverging from the object will emerge from the lens in a converging direction, and being thus received by an emmetropic eye adjusted for parallel rays, must meet in the vitreous and form circles of diffusion upon the retina, giving rise to one of the difficulties which the learner so often encounters and knows so little how to explain and remedy. Another advantage of this instrument which is not of least importance, is that it is always at our command and may be studied at times when persons can not be found willing to submit.

Having now shown that the ophthalmoscope is a simple instrument to manage and understand, and also pointed out when and what the difficulties in ophthalmoscopic examinations are, and having suggested a means by which to facilitate the study of this instrument and these difficulties, I hope I have done something to encourage and assist those who may be interested in understanding diseases of the eye.