#Lithographic printing by transfer from engraved plates.# An impression on transfer paper may be taken from an engraved plate and this laid down on the stone in a manner similar to that used in laying down the prints from the glass negatives in photolithography. Prints are then made from the stone the same as in photolithography, but with superior results as to clearness. This general process is extensively used in both map and chart publishing in this country, as it combines the advantages of the plate in preservation of the chart record and facility of correction, and the advantages of the lithographic printing in less distortion of the printed chart, ability to print more than one shade, and facility for large editions. As the transfer from the plate can be readily made it is also better applicable to small editions than is photolithography. It is, however, not as convenient in the latter respect as plate printing, and it does not give a resulting impression equal in clearness or durability to the impression directly from the plate. #Etching on copper# for chart publication has been recently developed in the Coast and Geodetic Survey. A finished tracing is made, the surface of a smooth copper plate is sensitized, and by exposure to the sun a print is made on the sensitized surface. It is essential to use an air-exhausted printing frame so as to get good contact between the vellum and the plate. The work is then etched into the copper and the plate cleaned and touched up, after which it may be used the same as a hand-engraved plate, either for transfer to stone or direct plate printing. The expense and time required in the etching process are much less than for hand engraving. The process has been successfully used for a number of harbor charts. The etching of course will be of the same scale as the vellum at the time of the print, and vellum varies somewhat in scale with weather conditions and age. Unless overcome by the substitution of some more invariable material in place of vellum, this might be an obstacle to the use of the process for general charts where a true scale on the copper plate is desirable because of future work to be done on the plate. It must also be taken into account that the etching requires a finished tracing in ink, which is not essential for the hand engraver; if, however, the chart is first published by photolithography, as is the usual practice in the Coast and Geodetic Survey, the same tracing is used for both processes.