430 GRAPHIC RECORDS OF RESPIRATION. L i3ooK 11, 



FIG. 85. APPARATUS FOR TAKING TRACINGS or THE MOVEMENTS OF THE 

 COLUMN OF AIR IN RESPIRATION. 



The recording apparatus shewn is the ordinary cylinder recording apparatus. 

 The cylinder A covered with smoked paper is by means of the friction-plate 

 B put into revolution by the spring clock-work in C regulated by Foucault's regu- 

 lator D. By means of the screw E, the cylinder can be raised or lowered, and 

 by means of the screw F its speed may be increased or diminished. 



The tracheotomy tube t fixed in the trachea of an animal is connected by 

 india-rubber tubing a with a glass T piece inserted into the large jar G. From 

 the other end of the "f" piece proceeds a second piece of tubing &, the end of 

 which can be either closed or partially obstructed at pleasure by means of the 

 screw clamp c. From the jar proceeds a third piece of tubing c?, connected with 

 a Marey's tambour m (see Fig. 36), the lever of which I writes on the recording 

 surface. When the tube b is open the animal breathes freely through this, and 

 the movements in the air of G and consequently in the tambour are slight. 

 On closing the clamp c, the animal breathes only the air contained in the jar, 

 and the movements of the lever of the tambour become consequently much 

 more marked. 



Below the lever is seen a small time-marker n connected with an electro- 

 magnet, the current through which coming from a battery by the wires x and y 

 is made and broken by a clock-work or metronome. 



tambour or with a receiver which in turn is connected with a tambour, 

 see Fig. 36, and Fig. 85. 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. 



If, a receiver being used, the open end of the | be closed, the 

 animal breathes into and out of the receiver, and the movements of 

 the tambour are greatly increased. This has the disadvantage that 

 the air in the receiver soon becomes unfit for further respiration. 

 A similar increase of the movements of the lever of the tambour 

 may be obtained by connecting a piece of india-rubber tubing to the 

 open end of the | . By increasing the length of this tube, or slightly 

 constricting it, the movements of the lever may be increased without 

 very seriously interfering with the breathing of the animal. 



In another method the movements of the chest are recorded. 

 When a small animal such as a rabbit is used, the whole animal may 

 be placed in an air-tight box, breathing being carried on by means of 

 a tube inserted in the trachea and carried through an air-tight orifice 

 in the wall of the box. By another orifice and tube the air in the box 

 is brought into connection with a tambour, which accordingly regis- 

 ters the changes of pressure in the air of the box produced by the 

 movements of the chest (and body) and thus indirectly the move- 

 ments of the chest. In man and larger animals the changes in the 

 girth of the chest may be conveniently recorded by means of 

 Marey's pneumograph. This consists of a hollow elastic cylinder, 

 or a cylinder with elastic ends, the interior of which is connected 

 with a tambour. By means of a strap attached to each end of the 

 cylinder the instrument can be buckled round the chest like a girdle. 

 When the chest expands, the ends of the cylinder are pulled out, 

 and the air within the chamber rarefied ; in consequence the lever 

 of the tambour connected with its interior is depressed ; conversely, 

 when the chest contracts, the lever is elevated. The pneumatograph 



