Nomogram type calculator slidable rule

Claim 1

In a nomogram calculating device of the type wherein a stylus point is pressed onto a transparent sheet and the pressure of the stylus point is transmitted through the transparent sheet onto a tacky, waxy surface layer of paraffin touching and immediately below said sheet to thereby form an image on the paraffin of the path taken by the stylus point, and wherein the image may be removed from the waxy surface layer by separation of said transparent sheet from said waxy surface layer, for the formation of subsequent images on different as well as the same areas of the waxy paraffin layer, the improvement comprising, a. a plurality of spaced data fields carried by a frame and stored on a plate above, parallel, and contiguous to said transparent sheet, b. means for mounting said waxy paraffin layer and said transparent sheet in said frame for sliding movement relative to said data fields, so that at least one zone of said paraffin layer is capable of being sequentially superposed beneath and with respect to each of said data fields, c. whereby a tracing on the waxy paraffin layer corresponding to the tracing of one data field may be superposed with respect to anothEr data field, d. an erasing bar positioned between the transparent sheet and the waxy paraffin layer, said erasing bar carried by and mounted on said frame, the erasing bar and the waxy paraffin layer being relatively movable, to thereby separate the transparent sheet from the waxy paraffin layer upon relative movement of the erasing bar and paraffin layer and thereby erase any images thereon.