SPIROMETER

n. Spir-o2m'e2t-u6r. From spirare, to breathe, and fierpov, a measure. Fr., spirometre. Ger., S., A them mes ser. Of Hutch in son, an instrument constructed on the principle of a gasometer, for measuring the various volumes of air in the lungs, especially the breathing capacity (q. v., under BREATHING). [J, 3, 40, 46.] Barnes's dry s. A s. invented by Barnes (1865), consisting of a flexible, hollow bag or cylinder fixed at the lower end and there connected with a tube through which the air is forced. At the upper end is a disc of wood from the centre of which rises a graduated tube communicating with the bag. The whole is contained in a frame. For an experiment, the graduated tube is closed at the top, air is blown into the lower tube, thus inflating the bag, and the amount of inflation is determined by the height to which the graduated tube rises. [J.] Brown's s. A simple arrangement of two rectangular boxes, one inside the other. The outer one is fitted with a mouth-piece, and the force of the air raises the inner one to a height marked by a gauge. [E.] Hutch in son's 8. A cylinder fitted with a mouth-piece and containing another cylinder which is supported by weights pa ing over pulleys and fitted with a gauge. [E.] [s. 522]