Abstract: A device for enabling a diver to determine his relationship to the true horizon in deep and murky waters or when physiological sensations are of little value is described. An attitude sensor, incorporating a series of mercury switches, usually at the back of the diver's helmet or head, is coupled to a series of light emitting diodes equally spaced around the periphery of the face plate of the diving mask or helmet so as to simulate the natural observation that the half space above the horizon is illuminated while the half space below the horizon is not.

Abstract: An insulating material suitable for use in a diver's garment or garment-like apparatus. The insulating material comprises a multiplicity of layers of a flexible, stretchable material. These layers include a central core consisting of a gas permeable, preferably multicomponent, layer of a material that is substantially non-compressible when at least partially evacuated and subject to hydrostatic pressure when immersed in water. Two further and gas impermeable layers are provided, each of these further two layers being of a stretchable material with the central core being disposed intermediate to said layers. When formed into a diver's garment, the peripheral edges of the insulating material are sealed, and sealable closure means are provided in at least one of the gas impermeable layers to communicate with the central core.

Abstract: A heat receiver is provided comprising a housing through which the breathing mixture passes in one direction and through which the exhaled breath passes in the opposite direction. The housing contains heat conductive elements through which the breathing mixture and exhaled breath pass and spacers positioned one between each pair of adjacent heat conductive elements. The spacers are poor heat conductors and non-hygroscopic to minimize moisture retention. In use, exhaled breath warms the heat conductive elements sequentially so that each element will be slightly cooler than the last element exposed to the exhaled breath. There will be minimal heat stored in the spacers and the moisture content of the exhaled breath tends to be carried through the device so that upon drawing breathing mixture through the device a substantial part of the sensible heat originally in the exhaled breath will be reclaimed by the breathing mixture. The latent heat originally in the exhaled breath will be lost.

Abstract: A device for enabling a diver to determine his relationship to the true horizon in deep and murky waters or when physiological sensations are of little value is described. An attitude sensor, incorporating a series of mercury switches, usually at the back of the diver's helmet or head, is coupled to a series of light emitting diodes equally spaced around the periphery of the face plate of the diving mask or helmet so as to simulate the natural observation that the half space above the horizon is illuminated while the half space below the horizon is not.

Abstract: A portable measuring device to provide a readout representing an equivalent windchill temperature or heat loss from exposed flesh in cold moving air. The device comprises a body having a channel through which moving air is conducted. A pair of oppositely disposed walls are part of the channel, and at least one of these walls is at least partially transparent. A windvane is disposed in the channel for deflection by the air moving through it. The windvane is supported from the body of the measuring device for pivotal movement. A thermometer is also supported from said body, and has graduations thereon to provide a measurement of the air temperature. Chart means are also provided on the body visible through one of said walls. First, second and third series of markings are on the chart means. At least a portion of the first markings is in alignment with the graduations of the thermometer. A portion of an other of the series of markings is oriented to be in alignment with the windvane upon deflection thereof.

Abstract: The instrument comprises means for measuring the ambient air temperature and providing a first signal proportional to the temperature, means for providing a second signal proportional to the non-evaporative rate of body heat loss in K Cal./m.sup.2 hr, and means for providing a third signal representative of the thermal insulation resistance of still air outside of clothing. Means is also included for measuring the fraction of full sunlight intensity reaching a person wearing the clothing, and for providing a fourth signal representative thereof, and further means for providing a fifth signal representative of the absorptance of the clothing. Further means adds the first signal to the product of the second and third signals and to the product of 230 and the third, fourth and fifth signals and substracts the product of 0.18 and the second signal, and provides an output signal, which is representative of the still shade temperature.

Abstract: A navigational device for use by underwater swimmers and divers in which a telescopically extensible boom is releasably and pivotally attached to the swimmer or diver. A compass device such as a magnetometer or fluxgate sensor is mounted at the end of the boom and is connected to an audio signal generator so that signals are generated if the swimmer deviates to either side of a predetermined course. The swimmer or diver wears a bone conduction transducer on each side of his head, which are connected to the audio signal generator via a gating device so that he can receive an audio signal, presented selectively on either side of his head, which is indicative of deviation from his predetermined course.

Abstract: Apparatus for determining the wet bulb globe temperature (WBGT) index of the surroundings constructed from a copper globe having a blackened exterior surface and provided with a fabric cover, which may entirely surround the globe or may be in strips or strands extending over the surface of the globe, with a source of water to maintain the fabric cover at least partially wet. A temperature sensing device, which may conveniently be a glass thermometer, as its sensing portion located at the center of the globe whereby a measurement of the wet bulb globe index of the surroundings can be obtained.