as in the foregoing, was the pain in the hypogastric or lower abdominal region. But, last summer, I was called to attend a Mrs. P. in her first accouchement, which was quite satisfactory, except that the pains were weak with long intermissions, necessitating an occasional drachm of the tinct. ergot., and terminated in about ten hours, the patient feeling pretty well exhausted. On the fourth following morning was called to see her, and requested from herself to bring something to quiet the nerves. On arrival I found her nerves quite unsettled-had not slept during the night, nipples very painful-looked depressed and complained of great weakness, dark circle under the eyes—articulation not so distinct as usual, which she ascribed to a feeling as of thickness of the tongue; had asked the nurse strange questions during the night during which time the bowels had operated twice; some tympanitis, pulse weak, quick and regular, skin cool and moistened with sweat, no pain in abdomen or pelvis, even by pressure. Supposing the trouble to be merely of the nerves, I prescribed morph. acet. and spirit ammon. arom. with rest and quietude, and solution of gutta percha tissue in chloroform for nipples. The second evening after, I was called to visit her again, and on arrival about 8 o'clock, to my great surprise, I found her quite incoherent and much prostrated high fever, skin hot and dry, tympanitis much increased, tenderness of hypogastric region, patient very weak, she thought she was improving, &c. Treatment as in other cases venesection to 12, sinapism to hypogastrium, pulv. opii. gr. j, et hydr. submur. gr. j every four hours, quietude, &c.

Next morning at 5 o'clock, was called again in haste, but on my arrival at 6 o'clock, she had expired. The nurse said she complained of nothing, but gradually sank.

I will leave your readers to draw their own inferences as to the treatment and the result; but for my part, if I ever have another case of this kind, the treatment will be of an exactly opposite character.

From the foregoing it must be evident to all unbiassed minds, that the types of two diseases were met with, which are very different in their symptoms, and require altogether different treatment; and consequently, that there is a radical error in the nomenclature of these puerperal complaints. According to the classification at present in vogue, every inflammation of almost any organ of the body, contracted from delivery to seven or ten days after is called puerperal fever-pleurisy for instance; and this fever was formerly described as being almost uniformly fatal. Now, however, the vast majority of this so-called fever recover. This improvement cannot be owing to a difference of treatment, as that which is now the most successful was practised to even a greater extent

formerly; but is explicable on the assumption, that the puerperal fever of the ancients, which was almost uniformly fatal, is now made to include their disease, and which yet retains its pristine malignity, and a great many other diseases of a simple inflammatory origin, and quite amenable to antiphlogistic treatment. It seems to me, therefore, that there are included under this specific term two fundamentally different diseases, viz: One having its origin in inflammation of one or more of the organs, usually those of the abdomen or pelvis, apparently in consequence of the ordinary exciting causes of inflammation-neither contagious nor infectious, may prevail epidemically, as other inflammations sometimes do, pneumonia for example, and is quite under the power of well directed antiphlogistic medication; and a specific fever, which has not its origin in inflammation of any of the organs but which may secondarily set up disease therein, is contagious and extremely fatal, requires a stimulant and supporting treatment, but which usually defies all medication. Dr. Churchill is one of those who favour the inflammatory theory, and he divides it into five varieties, depending upon the part inflamed, and recommends antiphlogistic treatment; but also states, with Dr. Tyler Smith, that cases occur without any inflammation manifested before or discoverable after death, and confesses that the latter are very fatal.

It is evidently wrong to include under and apply one specific name to a great many different diseases, particularly if the name be the name of one of the symptoms, because its tendency is to lead to routine, and to distract the attention from the true pathology. There is a strong tendency to treat the same disease in the same way under all circumstances, bearing a difference of degree; so, if one specific term be applied to the exanthematous affections, one can readily imagine what the treatment would be; the body would be kept warm as it should be in rubeola, or cool as it should be in variola, and the result would necessarily be disastrous. This generalization is injurious to the student, because having his mind impressed with the great mortality from puerperal fever, he is, in its treatment at first, anxious and meddlesome; but having had several cases as it ordinarily occurs, and conducted them to a satisfactory issue, he falls into the error of thinking he has hit upon the hitherto undiscovered means of successfully combating it, and his anxiety gives way to ill-grounded confidence and routine; but after awhile a true representative case of the malady occurs, and the patient becomes a sacrifice before he knows what he is about.

Clarke, C. W., Feb. 1866.

The Optical Defects of the Eye, and their Treatment, by the Scientific use of Spectacles. BY A. M. ROSEBRUGH, M.D.

(Read before the Canadian Institute, February 3rd, 1866.)

The following pages were written as an introduction to a course of lectures recently delivered by me on the diseases of the eye. I have not thought it necessary to alter the form, as I propose publishing them as a pamphlet, hoping that they may be useful, not only to the members of my ophthalmic class, but to Canadian medical students generally.

In their preparation, I must here acknowledge my indebtedness to the elaborate works of Mr. J. Z. Laurence and Mr. J. Soelberg Wells, of London, and especially to the very comprehensive treatise of Professor Donders, of Utrecht, published in 1864, by the New Sydenham Society.

CHAPTER I.-OPTICAL CONSIDERATIONS.

The eye is pre-eminently an optical instrument, and the phenomena of vision all depend upon the laws of optics. Hence, a knowledge of some, at least, of the elementary principles of light is essential to a correct appreciation of the physiology of the eye. The diagnosing of optical defects of the eye,-long and short sight, &c., &c., and their treatment with the scientific use of spectacles, require some knowledge of the laws of refraction, and the properties of convex and concave lenses.

The philosophy of the ophthalmoscope can hardly be understood unless the principles of both refraction and reflection are thoroughly mastered.

You will, therefore, I hope, not consider the time ill-spent if, before proceeding with the investigation of diseases of the eye-you review with me some of the elementary principles of optics which lie at the foundation of all ophthalmic science.

The nature of light is not known. I can no more tell you what light is, than your professor of physiology can tell you what life is. We know that the sun shines, but how it shines we cannot tell.

"Two different theories have been advanced of the more intimate nature of light." "One, the Newtonian (corpuscular) conceives that each luminous point is constantly giving off a succession of luminous corpuscles which follow each other in uninterrupted succession on an imaginary line or axis like a string of beads on a rigid thread."

The undulatory theory (Christian Huyghens') on the other hand considers space as pervaded by a subtle gaseous fluid or ether; that luminous bodies have the power of communicating to this ether a wave

motion which affects the retina the same as vibrations of the air affect the auditory nerve.

Sir John Herschel, speaking of the great ingenuity of the undulatory theory says, "if it is not true it deserves to be."

The sun is the great natural source of light; as it shines by its own light it is called self-luminous. The fixed stars are also self-luminous; so is a lighted lamp and bodies in a state of ignition. But most bodies by which we are surrounded, are seen only by reflected light. The light from an object seen by moonlight is reflected twice before it reaches the eye. The moon reflects the light from the sun, and the object the light which it receives from the moon.

Every luminous object gives off, or radiates, in every direction, an infinite number of straight lines of light. Each of these lines taken alone is called a ray of light. A bundle of rays is called a beam of light when the rays are parallel to each other. When the rays diverge from a luminous point or are made to converge to a focus they are called a pencil of rays thus:

Fig. 1 represents a pencil of rays diverging from a flame F, after passing through a convex lens they are rendered parallel and these parallel rays passing through the second convex lens B, the rays are converged to the point (focus) P.

The parallel rays may be called a parallel pencil; the diverging rays a divergent pencil, and the convergent rays a convergent pencil. The point where rays of light meet is called the focal point or simply a focus.

Strictly speaking, there is no such thing in nature as parallel rays; the nearest approach we have to it are the rays of light we receive from the sun and the fixed stars. Practically, we may consider rays of light parallel that are received by the pupil of the eye from objects that are twenty feet distant or any greater distance. Pencils of light from objects. less than twenty feet distant are more decidedly divergent.

A good illustration of a divergent pencil can be obtained from a lighted lamp or candle in a dark room. If a piece of card board, with a

small circular opening in it, be held near the lamp, you will have, upon the opposite wall, an illuminated spot of the same shape as the opening in the card, but very much larger.

This will prove not only that the rays diverge, but also that the rays proceed in straight lines. *

Convex Lenses:-We shall now proceed to the consideration of convex lenses, which, for our purpose, is the most important part of the subject. Lenses are made of various transparent substances as amber, alum, quartz, glass, diamond, and even of ice. Those in ordinary use are made of glass. When the two surfaces of a convex lens have the same degree of curvature, the lens is said to be equi-convex. When one of the surfaces is flat or plane, the lens is called a plano-convex lens. Glass spectacles used by old persons for reading, &c., are commonly made double convex. In order to simplify the subject as much as possible, let us confine our attention to lenses that are equi-convex.

In fig. 2 let A be the centre of the circle B C D of which A B is the radius, and let E be the centre of the circle F G H of which the radius, EF is equal to the radius A B. The circle F G H will be equal to the circle B C D. The part D H, common to both circles, represents a section of an equi-convex lens. The line A E is called the axis of the lens, and the line D H is called the diameter. The centre of the diameter

(where it is intersected by the axis) is the optical centre of the lens.

Reading glasses and burning glasses are examples of a double convex lens. Many of you have doubtless seen the experiment of setting fire to wood, paper, &c., by means of a burning or sun glass. The explanation

(Convergent pencils of light do not exist in nature. Parallel pencils or divergent pencils of rays can be rendered convergent by means of a convex lens. Thus in fig. 1, the rays diverging from F. are made to converge to P. by the convex lenses, A. and B.)