. The Journal of laboratory and clinical medicine . curve only 10 em. in height. Ac-cordingly, two tracings may be made above one another upon paper possessingthe usual breadth of 25 cue The writing lever consists of a delicate beam of wood, measuring 28 cm,in length. Its weight is accurately balanced by the weight G attached to theother end of the piston rod. Inasmuch as rods H and H^ are movable, the re-cording lever L may also be connected with the right end of the piston-rod,while weight G is attached to its left end. Another way of recording the volumes of the air respired is to attach as
. The Journal of laboratory and clinical medicine . curve only 10 em. in height. Ac-cordingly, two tracings may be made above one another upon paper possessingthe usual breadth of 25 cue The writing lever consists of a delicate beam of wood, measuring 28 cm,in length. Its weight is accurately balanced by the weight G attached to theother end of the piston rod. Inasmuch as rods H and H^ are movable, the re-cording lever L may also be connected with the right end of the piston-rod,while weight G is attached to its left end. Another way of recording the volumes of the air respired is to attach asmall weight to each end of the piston-rod and to equip one of these with adelicate writing lever which may be held against the paper of the kymographby a horse-hair weighted at its lower end. Lastly, the volumes of the air maybe read off directly from a scale {Sc) attached to the guard-rod H. Possibly the simplest way of calibrating the cylinder of this spirometer isto attach a large rubber tube to orifice A of the rotating disc and to permit its. Fig. free end to project into a vertical graduated glass tube tilled with water. Ifvalve Y is now adjusted to yield only expiratory currents of air, the volumeof each may be accurately ascertained by permitting this air to displace theNvater within the graduated tube. If the facial mask M is connected directly with tube A or A^ of therotating disc, the writing lever L will register a series of successive up anddown strokes which may be widely separated from one another at their basesby increasing the speed of the drum. Since the course of the air determinesthe direction of the movement of the piston, the upstroke may represent eitherthe inspiratory or the expiratory phase. In other words, the direction of move-ment of the writing lever depends upon the position of the rotating disc. Toillustrate this statement more fully, I have inserted in this place Fig. 3, inwhich the letters ./ E indicate the insi)iratory period, and the letters E
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