CHAP, ii.] RESPIRATION. 317 



fall and rise of the diaphragm, be registered, curves are obtained, 

 which, while differing in detail, exhibit the same general features, 

 and more or less resemble the curve shewn in Fig. 55. 



The movements of the column of air may be recorded by introducing 

 a T piece into the trachea, one cross piece being left open or connected 

 with a piece of india-rubber tubing open at the end, and the other con- 

 nected with a Marey's tambour or with a receiver which in turn is con- 

 nected with a tambour, Fig. 22, p. 140, and Fig. 56. The movements of 

 the column of air in the trachea are transmitted to the tambour, the 

 consequent expansions and contractions of which are transmitted to the 

 recording drum by means of a lever resting on it. The movements of the 

 chest-walls may be recorded by means of the recording stethometer of 

 Burden-Sanderson. This consists of a rectangular framework constructed 

 of two rigid parallel bars joined at right angles to a cross piece. The free 

 ends of the bars, the distance between which can be regulated at pleasure, 

 are armed, the one with a tambour, the other simply with an ivory button. 

 The tambour also bears on the metal plate of its membrane (Figs. 22 

 and 56, m',) a small ivory button (in place of the lever shewn in 

 Figs. 22 and 56). When it is desired to record the changes occurring in 

 any diameter of the chest, e.g. an antero-posterior diameter from a point 

 in the sternum to a point in the back, the instrument is made to encircle 

 the chest somewhat after the fashion of a pair of callipers, the ivory 

 button at one free end being placed on the spine of a vertebra behind 

 and the tambour at the other on the sternum in front in the line of the 

 diameter which is being studied. The distance between the free ends of 

 the instrument being carefully adjusted so that the button of the tambour 

 presses slightly on the sternum, any variations in the length of the 

 diameter in question will, since the framework of the tambour is im- 

 mobile, give rise to variations of pressure within the tambour. These 

 variations of the 'receiving' tambour as it is called are conveyed by a 

 flexible tube containing air to a second or 'recording' tambour similar 

 to that shewn in Figs. 22 and 56, the lever of which records the varia- 

 tions on a travelling surface. For the purpose of measuring the extent 

 of the movements the instrument must be experimentally graduated. 

 In Marey's pneumatograph, a long elastic chamber is used as a pectoral 

 girdle. When the chest expands, the girdle is elongated, and the air 

 within it rarefied, and the lever of the tambour connected with it de- 

 pressed : and conversely, when the chest contracts, the lever is elevated. 

 The pneumatograph of Fick is somewhat similar. The movements of the 

 diaphragm may be registered by means of a needle, which is thrust 

 through the sternum so as to rest on the diaphragm, the head of the 

 needle being connected with a lever. Various modifications of these 

 several methods have been adopted by different observers. 



As is shewn in Fig. 55, inspiration begins somewhat suddenly 

 and advances rapidly, being followed immediately by expiration 

 which is carried out at first rapidly, but afterwards more and 

 more slowly. Such pauses as are seen occur between the end of 

 expiration and the beginning of inspiration. In normal breathing, 

 hardly any such pause exists, but in cases where the respiration 

 becomes infrequent, pauses of considerable length may be observed. 



