In chronic defluxions of the eyes, and in the affection of vertigo, we are in the practice of dividing the arteries behind the ears. Having, therefore, shaven the hind part of the head, and marked with the fingers the position of the artery, which is easily discovered by its pulsation, and then having marked out the line of an incision two fingers in length with black ink, we cut down to the bone. When this does not succeed we must measure a distance of three fingers’ breadth from the ears, and then operate by making a transverse division of the artery until blood flow _per saltum_, and the instrument strike the bone. After a moderate evacuation of blood, the pericranium is to be divided, lest it become inflamed from the distension; and having scraped the bone we apply a wedge-like tent of linen to the wounds, and accomplish the cure by pledgets. But if, after all, the bone remain bare, we must have recourse to scraping it in like manner. * * * * * COMMENTARY. Our author’s description is mostly abridged from Aëtius (vi, 90), who copies from Severus. This operation is minutely described by Albucasis. (Chirurg. ii, 2.) He directs us to shave the head, and rub the parts behind the ears with a rough cloth until the arteries become visible. The course of the vessels is to be marked with ink, and they are to be divided with a sharp scalpel, the incision penetrating down to the bone. He says, however, that if the surgeon choose, he may introduce the scalpel below the vessel, and cut upwards. The length of the incision is to be two fingers’ breadth. Blood, he remarks, springs from an artery per saltum. About six ounces, more or less, may be taken. The operation is likewise mentioned by Avicenna (Cantic. iv,) and Averrhoes (in Cantic.); by Rhases (ad Mansor. vii, 21); and is described in exactly the same terms as our author’s by Haly Abbas. (Pract. ix, 4.) SECT. V.—ON ANGIOLOGY, OR SECTION OF THE TEMPORAL VESSELS, AND ON BURNING THE SAME.