With the second book of the Compendium the system of the discussion of diseases _a capite ad pedes_ is commenced, and produces some curious associates. To the modern physician the sudden transition from diseases of the scalp to fractures of the cranium seems at least abrupt, if not illogical. It seems, therefore, wiser, in a hasty review like the present, to take up the various pathological conditions described by Gilbert in their modern order and relations, and to thus facilitate the orientation of the reader. The second book then opens with a consideration of the hair and scalp, and their respective disorders. The hair is a dry fume (_fumus siccus_), escaping from the body through the pores of the scalp and condensed by contact with the air into long, round cylinders. It increases rather by accretion than by internal growth, and its color depends upon the humors. Thus red hair arises from unconsumed blood or bile; white hair, from an excess of phlegm; black hair, from the abundance of black-bile (_melancholia_), etc. The use of the hair is for ornament, for protection and for the distinction of the sexes. Numerous prescriptions for dyeing the hair, for depilatories (_psilothra_), for the removal of misplaced hair and for the destruction of vermin in the hair are carefully recorded. Three varieties of soaps for medicinal use are described, and the process of their manufacture indicated. The base of each is a lixivium made from two parts of the ashes of burned bean-stalks and one of unslaked lime, mixed with water and strained. Of this base (_capitellum_), two parts mixed with one part of olive oil form the _sapo saracenicus_. In the _sapo gallicus_ the base is made with the ashes of chaff and bean-stalks with lime, and to it is added goat's fat, in place of the oil. The _sapo spatareuticus_ is made in a similar manner, except that oil replaces the goat's fat and the soap is made only during the dog days, since the necessary heat is to be supplied by the sun alone. Among the diseases of the scalp attention is given to alopecia, dandruff (_furfur_), tinea caries and various pustular affections, fanus (favus), rima, spidecia, achora, etc. Caries was a pustular disease, in which bristle-like hairs formed a prominent feature. Rima was a name applied by the physicians of Salernum to a superfluity of hair. In addition to these diseases of the scalp, we find also descriptions of gutta rosacea, morphoea and scabies, a fairly extensive dermatology for this early day. In favus, Gilbert tells us that, after the removal of the pustules, there remain foramina, from which exudes a poisonous substance, resembling honey. Of course his system of treatment is rich in variety and comprehensiveness.