Rhases, Avicenna, Serapion, and Haly treat of the epiala, and the “frigus quod non calefit,” as varieties of the quotidian. Alsaharavius gives a very distinct account of the epiala. He says it arises from a gross vitreous phlegm, and is attended with internal heat, and cold of the extremities. The pulse is small and weak, the urine white and unconcocted, and the perspiration suppressed, owing to the constriction of the pores and thickness of the humours. He approves of giving emetics, attenuants, and calefacients. The lipyriæ are treated of by Serapion, Avicenna, Rhases, and Alsaharavius. They are said to be the counterpart of the epialæ, being distinguished by internal cold and external heat. Rhases describes the hepialus as consisting of internal heat and external cold. He says it arises from vitreous phlegm. The lipyria, he states, is one of the worst varieties of ardent fevers. The rigor without heat, or “frigus quod non calefit,” is a febrile affection still met with in warm climates. The term _typhus_, now generally applied to the common fever of this country, is used by Hippocrates, in his work on ‘Internal Affections,’ where he describes five varieties of the disease. They are cases of ardent fever, attended with stupor and insensibility. The term _typhodes_ occurs in Galen’s ‘Commentaries on Hippocrates;’ in his work, ‘De Diff. Feb.’ (i, 9); and ‘De Prognost. Puls.’ (ii, 9.) Leo defines a typhous fever to be one in which the heat is weak and concealed. (14.) It would appear that the fevers to which the ancients applied the term _typhoid_ were either intermittents or remittents. Isidorus thus defines typhous fevers: “Typhi sunt frigidæ febres, quæ abusivè typhi appellantur ab herbâ quæ nascitur in aquis quæ Latinè _forma_ atque _status_ dicitur: est enim accessionum revolutio per statuta temporum intervalla.” (Orig. iv, 7.) The word τύφος occurs in Marcus Antoninus (ii, 17), where Gataker remarks, “Est enim τύφος κυρίως idem quod κάπνος, fumus.” Salmasius gives the derivation of the term as follows: “τύφος proprie est fomes, τύφεσθαι enim ἠσυχῆ κάιεσθαι Græci exponunt.” (In Tertulliani Librum de Pallio Annot. 318.) Prosper Alpinus thus explains the nature of typhoid fevers: “Has febres exterius mites seu obscuras intus turbantes Græci _typhodes_ appellant, quippe quæ naturam multitudine humorum gravatam, ac fere suffocatam, incendium foras transmittere nequeuntem, significent. Hasque vulgus medicorum appellat, foris mites, intus conturbantes; suntque eæ omnes, admodum perniciosæ.” (De Præsag. Vita et Morte Ægrot. i, 10.) SECT. XXVII.—ON THE CONTINUAL FEVERS.