62 



COMPARISONS OF RESPIRATORY EXCHANGE. 



that when placed in the nostril the other end can be easily attached 

 to the connecting piece B (fig. 23) without stress being put upon the 

 nostril. The view at A (fig. 24) shows it as it appears from above 

 when placed in the nostril and at B from the side. 



Valves. The valves used in the Tissot method are the Thiry valves. 1 

 Two of these are shown in figure 23 (C and C). A very thin brass 

 flap, D, hinged on one edge, rests against a brass tube, E, 15 mm. in 

 diameter. The edge of the tube is tapered where the flap D rests 

 against it, so that there is a minimum amount of surface in contact 

 between D and E. The brass tube E is inserted in a collar F, which 

 screws into the ring G. This ring encircles a glass tube, H, 23 mm. in 

 diameter and 30 mm. in length. A collar, K, with attached brass tube, 

 /, fits over the end of the glass tube H. The glass tube is cemented 

 into the parts G and K by sealing-wax. The tee-piece B joins the two 

 valves and the nosepieces. When the valve is in action, the air enters 



FIG. 23. 



FIG. 23. Nosepieces and valves used with the Tissot method. 



A, A, nosepieces; B, tee piece connecting two valves C, C; D, flap of valve; E, inlet of valve; J, 

 outlet of valve; H, glass tube to which are sealed brass shoulder, K, and ring, G; F, threaded part 

 fitting into G; L, part of apparatus for registering respirations; b, thin copper flap to which are 

 attached two electrical contacts. 



FIG. 24. Modified glass nosepieces. 

 A, view from above when placed in the nostril; B, view from side when placed in the nostril. 



at E, raising the flap D, and leaves at J. The valves and nosepieces 

 are supported upon the head of the subject by means of straps or strings 

 connecting the valves with a small round cap which fits over the head. 

 With this arrangement the nosepieces can be forced into the nose and 

 it is possible for the subject to maintain any position. 



Apparatus for registration of respiration-rate. The number of respi- 

 rations in a particular experiment can be obtained by attaching to the 

 valves a fitting which contains a mercury contact of special design. 

 This is shown at L in figure 23. A perspective view is given in figure 25. 



1 Thiry, Recueil des travaux de la societe medicalc Allemande de Paris, 1365, p. 57. 



