Aetius lived in the first half of the sixth century, and compiled a voluminous treatise on medicine in sixteen books. He worked entirely with scissors and paste, but the result is the preservation to us of a large number of extracts from writers whose works would otherwise have entirely disappeared, and his work is of great value for the study of instruments. In 1534 an Aldine Edition of the first eight books was published, and, though a translation of the whole work was published by Cornarius in 1533-42 in Latin, six of the last eight books were never published in the original Greek. This is unfortunate for us, as for our purpose the original is the only thing of any great value, Greek being, as I have already pointed out, a language richer in compounds than Latin is, and lending itself better to the coining of special names for special instruments. Not that the sixteenth-century translator is ever at a loss for a turn by which to express himself in Latin, but the turn, as often as not, is by periphrasis just at the very point when we would have liked a very exact equivalent for the Greek. The translation of the part of the work of which we have the Greek shows that we cannot entirely depend on some of these periphrases even where they appear definite, as in some cases an unwarrantable assumption is made about the form of an instrument. Thus λιθουλκῷ is translated 'forcipe ad id facta' because in Cornarius's time the instrument used for extracting stone from the bladder was a forceps, whereas it is doubtful whether there was in the Roman period anything more than a scoop, and, therefore, we are not entitled to translate λιθουλκός by anything more definite than 'stone extractor', its etymological equivalent. Although, therefore, I have examined the latter eight books of Aetius in the Latin translation, and although they contain some of the most interesting information to be found in the whole work, I have been very chary about laying stress on any deductions drawn from the Latin translation only. It may be noted that there are two ways of referring to the different books in Aetius, according to whether the Greek text or the translation of Cornarius is meant. Cornarius arranged his version in four tetrabibli of four books each, whereas the Greek text is simply numbered from i-viii. 'No vii.' of the Greek text is, therefore, called by Cornarius 'Tetr. ii. lib. iii.' The eleventh book was published by Daremberg in his edition of Rufus (1879), and the twelfth book was published by Costomeris at Paris in 1892. Pliny the Younger. Plinius Secundus (Rose, Leipzig, 1875). The writings of Pliny contain little information of any kind and are absolutely of no use for our purpose.