Paper, 'On a pneumatic analogue of the Wheatstone bridge' by William Napier Shaw Shaw writes: 'When fluid flows steadily through an orifice in a thin plate, the relation between the rate of flow, V, measured in units of volume of fluid per second, and the head H (the work done on unit mass of the fluid during its passage) may be expressed by the equation:— H = RV^2, where R is a constant depending upon the area of the orifice, If the head be measured in gravitation units, R is equal to 1/2gk^2a^2, where g is the acceleration of gravity, a the area of the orifice, and k the coefficient of contraction of the vein of fluid, a factor which is independent of the rate of flow.' Annotations in pencil and ink. Includes a sketch and diagram of Shaw's pneumatic analogue of the Wheatstone bridge. Subject: Pneumatics / Fluid dynamics / Electricity Received 31 March 1890. Read 24 April 1890. Communicated by Lord Rayleigh [John William Strutt]. A version of this paper was published in volume 47 of the Proceedings of the Royal Society as 'On a pneumatic analogue of the Wheatstone bridge'. 1890