605 was the cause of obstruction. A surgeon had made an unsuecessful attempt to remove the supposed polypus by the forceps: this caused much suffaring; and it was at last discovered that the obstruction was due to thickening of the turbinated bones. Czermak, in the last German edition of his work,* gives a good illustration of the value of rhinoscopy in correcting an erroneous diagnosis. A young man deaf on the left side was found to have a tumour at the back of the nostril, which conveyed to

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... e finger the impression of a polypus. An operation was contemplated, but a rhinoscopic examination discovered a tapering swelling of the mucous membrane, nearly as thick as the finger, surrounding the orifice of the left Eustachian tube; also great swelling of the middle and inferior turbinated bones; bat no polypus, nor any tumour which an operation could have removed or lessened. Note.-Mr. Ernest Hart, ophthalmic surgeon to St. Mary's Hospital, has been good enough to send me, at my request, the following note on Ophthalmoscopy as compared with Laryngoscopy. I am happy to avail myself of his clear statement of the optical principles which render a perforated reflector ,necessary in the one case and not in the other. "The light which penetrates the eye is not wholly absorbed by the choroidal pigment, and must therefore pass out again ; and, obviously, if the eye of an observer were brought into such a position as to receive these rays which emerge, he would see the image of the tunics behind the retina, which act as the refiecting screen. But as the eye is an optical apparatus composed of refracting media (lenses), the rays in passing out are refracted anew, and the image of the retina is formed in the I air (and according to the law of conjugated foci) on the same ' , side as the luminous object, and at a distance regulated by the accommodation of the eye, the distance of the object, and the shape which the lens of the eye assumes, for the purposes of distinct vision. Hence, if a light were placed in front of an eye, and the head of an observer could be interposed be. tween that light and the eye to be observed, he should, at the distance of distinct vision, be able to see the retina by virtue of its reflected image. But the head of the observer stops the light from entering. This difficulty, however, is got over by pnttiug a light by the side of the eye to be observed, and with a concave mirror reflecting the light into that eye. If now the eye of the observer be placed at a small aperture in the mirror, he will be in a position to receive the luminous ray emerging from the eye observed and returning towards the mirror, and therefore to see the image of the ifandus oculi from which it is reflected. I think this diagram makes this part of the matter sufficiently clear. r a is the circle of diffusion of the retina, and the lines indicate how the rays reflected from that position will be refracted by the media of the eye, and form at r' a' a real, enlarged, but inverted image of the fundus of the eye. And it will be seen also that to get this image the mirror must be placed at the limit of distinct vision-where the image is formed, and which varies for each eye. There are other points necessary to be attended to in ophthalmoscopy, and which render it difficult for beginners. But none of these exist for laryngoseopy. Laryngoscopy requires only the illnmination of plain or curved surfaces and tubes; and as there a"e no series of lenses through which the rays reflected by them are refracted, so none of these optical difficulties exist. The practice of looking through a central aperture of the reflecting mirror used is one which has no foundation that I can perceive in any law or rule of optics, and is simply an inconvenient restriction of the field of vision and the facility of observing, which may probably have arisen from the mechanical imitation of the practice of ophthalmoscopy, without sufficient consideration of the peculiar optical difficulties which exist in the lai ter art.