Abstract: Apparatus for testing the performance of electrical machines by producing a direct digital readout and display of per unit rotor slip in electrical motors from no load condition through loads in excess of maximum rated load. The apparatus includes speed sensing means for detecting the rotor speed of the motor under test and means for producing a voltage output that is proportional to the rotor speed. A reference voltage is developed by sensing the frequency of the input voltage to the motor under test. The difference between these two signals, representing the actual rotor speed and the synchronous rotor speed, is divided by the reference voltage to produce the per unit slip of the motor under test.

Abstract: An amusement and instructional coloring book for the blind wherein the images are recessed into pages of the book to form a tactual image outline for defining the area to be colored. Raised border lines may also be provided to demarcate various portions of the image. A legend written in braille and typescript is also provided for defining the colors of the respective portions of the images. The coloring means also have corresponding visual and tactile indices thereon. Other features include means for the blind to appreciate the actual life-size of the images, variable extents of recessions of the image portions for imparting depth perception to the blind, special textures of the images to impart tactual qualities of the real-life images, and the provision of special paper adaptable to be colored completely by feel.

Abstract: A power transmission belt having the form of a Mobius strip with a single half twist consisting of a laminated structure assembled from a single strip of flexible material. The flexible material may be an adhesive tape or similar material having an adhesive surface on one side thereof, and a friction surface on the other side thereof. The laminated structure is assembled by first, forming an open loop with a first end portion of the flexible strip of material, and secondly, twisting said end portion 180.degree. about its longitudinal axis so as to place the adhesive surface of the twisted end in intimate face-to-face contact with the adhesive surface of a remaining portion of the flexible material, and thirdly, pressing together the adhesive surfaces of the remaining portion of the strip of material and the closed preformed loop in a manner whereby a laminated structure is formed from several congruent layers of said flexible material.