These medieval portative organs, so extensively used during the 14th and 15th centuries, were revivals of those used by the Romans, of which a specimen excavated at Pompeii in 1876 is preserved in the Museo Archeologico Nazionale Napoli. The case measures 14½ inches (36.8 cm) by 9⅓ inches (23.7 cm) and contains nine pipes, of which the longest measures only 9¾ inches (24.8 cm); six of the pipes have oblong holes at a short distance from the top similar to those made in "gamba" pipes of modern organs to give them their reedy quality, and also to those cuamboo pipes of the Chinese sheng, which is a mouth organ furnished with free reeds. From the description of these remains by C. F. Abdy Williams, it would seem that a bronze plate 11½ inches (29.2 cm) by 2¾ inches (7.0 cm) having 18 rectangular slits arranged in three rows to form vandykes was found inside the case, with three little plates of bronze just wide enough to pass through the slits lying by it; this plate possibly formed part of the mechanism for the sliders of the keys.