Page:An outline of English phonetics ... with 131 illustrations (IA cu31924027389505).pdf/36

18  to slide the wire along inside the tube. The wire is of such a length that when the handle D is at the end A of the slot, the upper end of the wire is just within B. Consequently when the handle D is pushed to the other end C of the slot, the wire projects from the end of the tube at B to a distance of 4.5 cm. E is an attachment called the “tooth-stop”. It is so made that when the projection points downwards it can slide along the tube, but when the projection points upwards it is fixed. FGH is a wire handle. In taking measurements the tooth-stop is adjusted at any required point and the projection then turned upwards so as to fix it. The instrument is then held with the 3 middle  fingers through the holes F, G, H, and the thumb on the handle D, and inserted into the centre of the mouth as shown in fig. 13. The handle D is then pushed along by the thumb until the end of the wire touches the tongue. The instrument is then removed from the mouth and the position of the end of the wire recorded by applying it to a previously prepared outline diagram of the section of the palate. By adjusting the tooth-stop at different points, the position of a number of points on the surface of the tongue may be recorded and diagrams showing the position of the centre line of the tongue obtained. Further points may be recorded by using another tooth-stop without the two projecting pieces of metal; the instrument is than kept in position by holding it in such a way that the tube is supported at two points, viz: the edge of the teeth (at the tooth-stop), and either at the teeth-ridge or at a point of the hard palate.

*85. The relative heights of the tongue in pronouncing some vowels may be demonstrated roughly by means of a quadrant indicator (fig. 14). The principle of the apparatus is as follows. A rubber tube T to which exploratory bulbs, embouchures, etc. (Chap. XXI), may be attached, communicates with a small elastic bellows B. To the bellows is fitted a pointer P, the further end of which is made to move along along a quadrant Qq when the bellows is expanded. When the bellows