Abstract: In order to provide a simple design of ventilation device which has a relatively open aperture of pleasing aesthetic appearance, there is provided a face 2 for facing into a room, the face including an aperture 3. Three closure parts 5 are provided for closing the aperture 3. The closure parts 5 are rotatably mounted adjacent to the aperture 3 about pivots 9 located around the periphery of the aperture. A drive means is provided for moving the closure parts between an open position and a closed position. A suitable fan 6 can be provided for drawing air through the aperture when the closure parts are in the open position. In a first aspect of the invention, the closure parts 5 each comprise closures surfaces having edges, the edges abutting one another in the closed position. In a second aspect of the invention, there is drive member 12 for contacting a drive part 11 of a closure part 5, the drive part 11 being located close to the pivot 9.

Abstract: In a measuring instrument of the kind in which an axial movement of an input member is required to be converted into a rotary movement of an indicating member, such as a pointer movable across a scale, the input member acts against a cantilever mounted spring. The indicating member is pivotably mounted adjacent the free end of the spring for angular motion in a plane substantially perpendicular to the plane of deflection of the spring by the input member. Co-operating means, respectively on the indicating member and the free end of the spring, are magnetically attracted into contact with each other for converting motion of the spring into motion of the indicating member and preferably these co-operating means are a cam or ramp of part helical configuration on the spring and a follower on the indicator, one or other of the cam or the follower being a magnet.

Abstract: A device for measuring the flow of a fluid in a pipe by creating aneasily measurable pressure differential which is related to flow comprises a diaphragm transversely contained in the pipe or an associated branch pipe. The diaphragm has a multiplicity of closely spaced fluid flow holes which are so shaped as to increase fluid flow velocity through the diaphragm, and means are provided downstream faces of the diaphragm said means being intended to be connected to a differential pressure indicating or recording instrument from which a fluid flow measurement can be derived.