There are fine specimens of the catheter, both male and female, in the Naples Museum. The male catheter is from the 'House of the Physician' in Pompeii. It is 24 cm. in length and is about the size of a No. 11 English. It has two gentle curves, so that it closely resembles the instrument reintroduced by Petit in the eighteenth century. See Pl. XLV, fig. 1. A catheter of similar shape, but broken in three pieces, was found by some workmen at Baden in the Seventies. They were given by Dr. Wagner, of Baden, to Mr. Atkinson, M.P., London, and are possibly now in some English collection (Brunner, _op. cit._ p. 42). In the excavation of the Roman Military Hospital at Baden, 1893, a fragment of a catheter was found, and is now in the possession of M. Kellersberger. It consists of the curved part of a catheter, and it is 13 cm. long and about the size of a No. 10 English. The curve is considerably greater than that of the Naples specimen (Un Hôpital Militaire Romain, planche ix). The female catheter in the Naples Museum is 0·98 m. long, and of the same diameter as the male one. It is straight (Pl. XLV, fig. 2). _Bladder Sounds._ Had the ancients solid bladder sounds? They must have been well aware of the characteristic grating sensation conveyed to the skilled hand on striking a stone with a metal instrument, for we have several references in the classics to the manœuvre of pushing back, by means of a catheter, a stone impacted in the urethra. Rufus of Ephesus (Περὶ λιθιώσης κύστεως) says of impacted urethral calculus: 'Those that are stuck fast push back with the catheter if you prefer not to do lithotomy' (ἐρείδοντας οὖν εἰ μὴ θέλοις τέμνειν ἀπῶσαι τῷ αὐλίσκῳ). Soranus (II. xviii) says if a stone is the cause of dystocia we must push it out of the neck of the bladder into the bladder with a catheter (καθετήρ). The word Rufus uses puts it beyond doubt that a hollow tube is meant, or we might have argued that καθετήρ did not necessarily mean a hollow tube, since Hippocrates uses it in the sense of a uterine plug (ii. 830). Yet strange to say, the sensation conveyed to the hand and ear on striking a stone with a metal instrument is nowhere definitely given as a cardinal symptom by a classical writer.