Abstract: A self-contained grinder attachment employs a rigid housing having an electric motor mounted thereon for driving both a grinding wheel and a blower which sucks air and loose particles entrained therein from the grinding area, the shaft on which the grinding wheel is mounted being connected to the housing by flexible and resilient connections thereby to isolate the grinding wheel from vibrations originating in the motor and in the lathe itself.

Abstract: A rotor is suspended from a body member which is mounted by two sets of bearings for substantially free pivotable movement about two orthogonally disposed intersecting axes, the axis of rotation of the rotor intersects the point of intersection of the two bearing axes, and a level indicating device is mounted to the body member.

Abstract: Method for substantially improving the shadow detail and color spectrum range of multicolored lithographic reproductions including the preparation of and printing with standard halftone printing plates and overprinting with a secondary printing plate made from a color separation used in making the halftone printing plates; the secondary printing plate being made from a secondary image exposed through a random pattern screen.

Abstract: A portable bubble balancer incorporates a wheel support and pivot assembly which is spring biased in an upward direction into an interlocked position with the base of the balancer to prevent pivoting of the wheel support in the absence of a wheel thereon.

Abstract: An improved two printing step process for reproducing visual subject matter including the making of a secondary printing plate with a positive image random pattern screen and printing a substrate sequentially and in registry with the secondary printing plate and a master printing plate made with a conventional half tone screen. The random pattern screen is a positive image phototransparency having a large plurality of irregularly shaped highlight areas and contrasting shadow areas per square inch, an optical density from about 0.17 to about 1.6, a contrast factor from about 0.75 to about 1.5 and a transparency factor from about 0.25 to about 0.60. The random pattern screen is made from a transparent plate having light disruptive projections on its surface. A negative and a positive phototransparency of the transparent plate are made while controlling exposure and developing conditions to produce a positive image screen having the desired characteristics.

Abstract: A diving snorkel has a flexible, tubular section having a substantially smooth inner surface to permit laminar air flow therethrough.