Cælius Aurelianus, however, disapproves of this practice in cases of cephalæa and epilepsy. The Arabians were even more partial than the Greeks to burning the head in these and other complaints. See in particular Albucasis, whose description is very minute. In cases of cephalæa he recommends the cautery to be applied to the occiput, but cautions against touching the bone lest it produce violent pain. He directs us to be careful to avoid muscles, nerves, and arteries. Avicenna, Rhases, Mesue, and Haly Abbas recommend the operation, in the most unqualified terms, as a powerful remedy in the cases mentioned by our author. Avenzoar, however, condemns the unguarded application of the burning iron to the head. Guido de Cauliaco recommends the cautery in cases of hydrocephalus (ii, 2, 10). Brunus also applied it for hydrocephalus, (ii, 17.) But see in particular Lanfrancus (III, iii, 18.) Fabricius ab Aquapendente states that from the most ample experience he had ascertained the good effects of applying the cautery over the sutures of the skull in various complaints, especially asthma, consumption, and all cold defluxions from the head to the chest. He gives a full account of the operation. (Œuvres Chirurg. ii, 1.) But see De Haën. (Rat. Méd. t. iii, p. vi, c. 6.) SECT. III.—ON HYDROCEPHALUS. The hydrocephalic affection is so named from the peculiarity of the fluid, it being of a watery consistence. It occurs in infants, owing to their heads being improperly squeezed by midwives during parturition, or from some other obscure cause; or from the rupture of a vessel or vessels, and the extravasated blood being converted into an inert fluid; or from rarefaction, the matter exuding and lodging between the skin and the pericranium. For the fluid is formed either between the pericranium and the skin, or between the pericranium and the bone, or between the bone and the meninx. In those cases, therefore, in which the fluid is formed between the skin and the pericranium, there is a soft tumour, all of one colour, and without pain, accompanied with an elevated swelling, having only a thin substance intervening between it and the fingers, readily yielding and again resuming its form. When it is seated between the pericranium and the bone, all the other appearances are the same, but the swelling is harder, yields more slowly, seems to be felt through thicker substances, and is more painful. When the fluid is seated between the meninx and the bone, there will still be a swelling, but not of so yielding a nature, nor so easily felt, only it yields to the application of strong pressure; for the bones of infants, being recently formed, are of a more yielding nature; and this is more especially the case when, owing to enlargement of the sutures, the fluid escapes outwards. This is readily ascertained from the circumstance, that by pressure of the fluid it retreats to the deep-seated parts. In such cases the pain is