Rhases borrows his account mostly from Antyllus and our author. Upon his own authority, however, he recommends bandages with compresses. He also approves of applying the actual cautery over the sutures. He further recommends friction and burning the temporal veins. Avicenna borrows freely from Aëtius and our author, and supplies no new views of practice. When water is collected in the anterior ventricles of the brain, Avenzoar, although in general no advocate for the actual cautery, directs us to apply it over the sutures. Albucasis says that he had only known hydrocephalus internus in infancy, and in every case it had proved fatal. However, he describes the operation of evacuating the collection in much the same terms as the Greeks. He warns the operator to avoid wounding an artery, lest the evacuation of blood should occasion immediate death. Alsaharavius mentions the frequent occurrence of the disease in sheep. Haly’s treatment is the same as our author’s. The hydrocephalus externus is now scarcely mentioned, and the existence of such a case has been even questioned. Van Swieten allows the reality of it, but says that it is of rare occurrence. (Comment. 1217.) We are disposed to think that the cases described by our author must have been collections of lymph, or pus occasioned by external injuries forming between the integuments and the bone. Modern pathologists admit the reality of collections of serum and pus between the bone and the dura mater. We may further mention that the earlier modern authorities approve of the cautery in the present case. See Guido de Cauliaco (ii, 2, 10.) The late Baron Larrey was a decided advocate for the application of moxa in this complaint. Henricus Regius directs us to evacuate the water slowly by making a small incision and introducing a silver canula. (Animad. Medic. 13.) Though recent experience does not give much encouragement to the operation, it sometimes happens that it is attended with success. Fabricius gives the same account of these cases as the ancients. (Œuv. Chir. ii. 22.) SECT. IV.—ON ARTERIOTOMY.