Abstract: A back pack formed of spaced apart hollow tubular members open at the lower end where each support member receives a shaft with each of the shafts supporting an axle extending therefrom and a wheel on each axle.

Abstract: A wide angle attachment adapted to be used with a prime lens. The lens comprises four elements in three groups. The combination of the attachment with a prime lens results in a lens system having a larger field of view than the field of view of the prime lens by itself.

Abstract: A solar heat energy collection system of the natural circulation type where the heat store is located above liquid cooled collectors. The system utilizes at least two liquids, the first is a non-freezing liquid which circulates between a heat store tank and the collectors, the second liquid is less dense than the first and immiscible therewith and acts as a heat store and also to supply the heat load. A third liquid less dense than the second and immiscible therewith may be utilized to supply the heat load. In this latter situation, the second liquid acts only as a heat store.

Abstract: An apparatus for crushing articles, such as aluminum beverage cans. The crushing apparatus comprises a rotatable, polygonal-shaped drum having blades mounted on each flat outer surface of the drum which project outwardly beyond the respective surface. The articles to be crushed are introduced into the area between the drum and a spring-loaded pressure plate, and on rotation of the drum, the blades engage the articles and move them into the nip between the drum and pressure plate to crush and flatten the articles. The apparatus also includes a quick release mechanism in which the pressure plate can be readily released to correct a jamming situation.

Abstract: A fume hood removes cooking odors such as grease from the air by providing positive contact with a recyclable water-detergent solution, thus serving to condense and emulsify the grease and thereby remove it. Positive contact with the water is caused by having a water-washed screen across the inlet of the hood, the screen having a mesh designed to cause a close interweaving of the air and water. The air then passes through the remainder of the hood and any remaining grease is removed by turbulent contact of air and water in the passage or along the inner sides of the hood. Through a series of one or more sloping dividers in the exhaust hood, the input recycled water may also create additional "waterfall" washing steps.The unit is maintained substantially at room temperature, even though receiving heated contaminated air, due to heat absorption by water evaporation in the washing process.

Abstract: A projection lens for a cathode ray tube comprises three groups. The overall positive power of the lens is provided by the first and second groups. The third group of negative power primarily corrects for Petzval curvature. In one form, the second group comprises a bi-convex element and a positive element. In preferred forms some of the lens surfaces are aspheric.

Abstract: A weighing device using an electromagnet to attract a load bearing member where the balancing force is sensed using a Hall effect device to sense the force of the magnetic field. Means are provided to produce a signal which is linearly proportional to the weight of the object being weighed.

Abstract: A retrofocus lens having a field angle of up to 76.degree. and comprising as few as six elements. A strongly negative front group of only two elements contributes to the compactness of the lens.