37 HEAT-SENSITIVE CELLULOSIC SHEET MATERIAL FOR MAKING DUPLICATE COPIES OF TYPED OR PRINTED MATTER, SAID CELLULOSIC SHEET MATERIAL BEING ADAPTED FOR USE IN A MACHINE PROVIDING AN INFRA-RED RAY SOURCE, SAID INFRA-RED RAYS BEING CONVERTED TO A HEAT PATTERN BY THE TYPE FACE ON THE ORIGINAL TYPED OR PRINTED MATTER, SAID HEAT PATTERN ACTING UPON SAID SENSITIZED SHEET TO RENDER A DUPLICATE COPY OF THE ORIGINAL MATTER VISIBLE THEREON