Making models in relief in gelatine by photographic processes

Claim 1

IN A PROCESS OF PRODUCING MAPS SHOWING DETAILS OF BOTH THE HORIZONAL AND THE VERTICAL DIMENSIONS OF A TERRAIN, THE STEP SO PROVIDING A MAP SHOWING SUCCESSIVE CONTOUR LEVELS, MAKING A SEPARATE IMAGE RECORD ON SHEET MATERIAL OF THE OUTLINE OF EACH OF SELECTED CONTOUR LEVELS OF THE TERRAIN, EACH OF SAID IMAGE RECORDS HAVING A LIGHT-CONTRAST BETWEEN AREAS ABOVE AND AREAS BELOW THE CONTOUR LEVEL REPRESENTED BY THE RESPECTIVE IMAGE RECORD, PHOTOGRAPHICALLY REPRODUCING EACH OF SAID IMAGE RECORDS ON A SHEET OF GELATINOUS MATERIAL SENSITIZED SO THAT THE SOLUBILITY OF THE GELATINOUS MATERIAL VARIES WITH EXPOSURE TO LIGHT, REMOVING THE MORE SOLUBLE GELATINOUS MATERIAL SO THAT THE AREA OF THE GELATINOUS SHEET ON ONE SIDE OF THE CONTOUR OUTLINE IS THICKER THAN ON THE OPPOSITE SIDE, AND SUPERPOSING SAID GELATINOUS SHEETS IN REGISTRATION WITH ONE ANOTHER TO FORM A RELIEF REPRESENTATION OF SAID TERRAIN.