Abstract: The subject indicator is a lightweight conical or cone-like member attached to a test surface at its apex by a flexure pivot. The indicators are useful, in a range of sizes, for providing visual indication of the direction and state of fluid flow past the attachment point of each indicator. The flexures may be made of string, cord or the like or, for higher temperature applications, one or more links of chain. The indicators are stable in action and do not whip.

Abstract: A system for photographically displaying the magnitude of a physical variable. In one embodiment, a sensor mounted on a movable probe produces an electrical signal indicative of the physical variable. The electrical signal then drives a lamp which is also mounted on the movable probe. A photographic time exposure of the lamp made while the probe scans an area provides a two-dimensional map of the physical variable. In another embodiment, a position transducer measures probe movement to provide an output indicative of the position of the sensor. The transducer output drives a positioning mechanism on which the lamp is mounted so that movement of the lamp corresponds to the movement of the sensor.