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equals/, but is considerably larger. If we take the Engli.sh inch, then the radius must be, when we take one metre as 39-5 English inches, as Landolt does, 41-87, or very nearly 42 inches. I think, moreover, it is a mistake to say "that most of the lenses used in this country are ground to the Eng- lish inch." I am informed both by Quanto Costa Levitra 20 Mg Mr. Hunter and by Mr. Meyrowitz that the glasses in their test cases as well as those in their spectacles are of French manufacture, and con- sequently are ground, not to the English inch, but to French measurements, and I am inclined to think, if the truth were known, it is the same with all the principal dealers. More- over, from the fact that the numbers on the French glasses of the old system happen to correspond to the focus ex- pressed in English inches, it has been pretty widely sup- posed, especially by opticians, that these glasses are ground to the English scale. This is, however, an error which depends again on the index of refraction which makes a glass ground, for example, on a radius of 36 French inches correspond to a focus of 36 English inches. It was this vvhich led Mr. Meyrowitz to state that "all trial- case lenses are numbered in English inches, and that, conse- quently, 40 is nearer to 1 D than 36." Nor is it correct to suppose that, with an index of re- fraction of 1-53, the radius of a lens, "in order to have a focus of one metre, must be 37 French inches." On the con- trary, such a lens must have a radius of 39-22 French inches. This follows directly from the formula/: 2 (n-1)- r =1-06 X 37 — 39-22 French inches, and, Quanto Costa Levitra 20 Mg as a matter of fact, 1 D is not ground on a radius of 1 metre, but on a radius of 1-06 metre. Even Dr. Burnett, in his own trans- lation of Landolt's work, says : " Thus, for an index of re- fraction of 1-53, a lens of 37" = 1 metre focal distance should have a radius of curvature of 39-16";* not, as he now says, "of 37 French inches." Landolt gets 39-15" in- stead of Quanto Costa Levitra 20 Mg 39-22, probably becau.se he takes the metre, not, as stated in the text, as equal in round numbers to 37", but to 36-94, which is more exact. If we take, as Nagcl does, an index of 1-54, tlien the radius would have to be 39-96 French, and 42-66 English inches. If, however, we take what is known as " double extra flint-glass," used for optical purposes, and which has an index of refraction of 1-71, the radius would have to be 52-54 French, and 56-09 English inches (taking the metre as equal to 39-5"). Thus, Quanto Costa Levitra 20 Mg starting with an index of re- fraction of 1-5, we may have a set of glasses with the identi- * "Examination of the Eyes," p. 87 July 24, 1886.] MOSELET: CICATRICIAL PLUG. 97 cal focus of one metre with a radius which varies from 37 to 52-54 French, and from 39-5 to 56-09 English inches. This immense variation is due solely to the index of re- fraction, and I have dwelt upon it because I wish to empha- size as strongly as I can the necessity for those who do not understand even the rudiments of optics to become thor- oughly familiar with the law which in its simplest form makes the focus of a biconvex glass equal to its radius, and because I desire to foster in every way in my power the growing inclination on the part of the general practitioner to use the ophthalmoscope, not to discourage him with technicalities. When the beginner has once mastered the few great principles upon which refraction depends, so far as the instrument is concerned, he can then turn to minutiit which, though simple enough in themselves, are, it would seem from the above, at times confusing even to the trained ophthalmologist. THE INFLUENCE, FROM A CLINICAL «TANDI'()INT, OF CICATRICIAL TISSUE IN THE Quanto Costa Levitra 20 Mg ANGLES OF THE LACERATED CERVIX.* By WILLIAM E. MOSELEY, M. D., BALTIMORE. MD. I HAVE found it impossible to formulate a Quanto Costa Levitra 20 Mg title that will convey to you concisely, and at the same time with any- thing like exactness, the character of the short paper I wish to present to your notice. Just what I desire to accomplish is this : To demonstrate, by exclusion, the influence that hard, or the so-called cicatricial tissue, deep in the angles of the lacerated cervix, has in causing the many nervous phenomena, such as headaches, general neuralgias, and gen- eral nervous irritability, which have been commonly in- cluded under the head of reflex nervous symptoms, and in causing, or at least perpetuating, the ana?raia which al- most invariably marks those cases Quanto Costa Levitra 20 Mg of neglected laceration in which we are called to operate. Besides this, I would enter an earnest plea for the most scrupulous adherence to the rules laid Quanto Costa Levitra 20 Mg down and repeatedly emphasized by our com- mon teacher, Dr. T. Addis Emmet, as to Quanto Costa Levitra 20 Mg the removal of all hard tissue from the angles before closing them. Of all the great mass of material one finds in print upon this subject of lacerated cervix, but very little takes into account the fact that such hardened tissue as that spoken of exists in the angles. Some writers deny its Quanto Costa Levitra 20 Mg existence, and of those who do recognize it but few accord it any position as a factor in the causation of the long list of symptoms which mark that condition of extreme invalidism that follows and has repeatedly been proved to depend upon the original injury. For example. Dr. W. Gill Wylie ("Am. Jour, of Obstet," Jan., 1882, p. 92) states that there is no such thing as a "cicatricial plug" or mass of hard, fibrous tissue in the angles of any lacerated cervix. Dr. T. G. Thomas, whose work is probably more extensivel}' used than any other as a text-book, does not mention the subject. Dr. Goodell gives it a considerable notice, but with so many wet blankets subsequently applied as to have