The expression of scales by miles to the inch or inches to the mile is the more familiar. The expression of scale in the manner used by the Coast Survey and by most of the European countries, by standard fractions as 1/80000, meaning that any distance on the chart is 1/80000 of the actual distance on the earth, has some advantages. For instance, the relation of these fractions gives at a glance the relation of the scales of the charts. Thus a 1/80000 chart is on a scale five times as large as a 1/400000 chart. For the more important harbors charts have been published on several different scales to meet various needs. Thus New York Harbor is shown on charts of scales of 1/10000, 1/40000, 1/80000, 1/200000, 1/400000 and 1/1200000, each of course including a different area. [Illustration: FIG. 26. NEW YORK HARBOR, PORTIONS OF CHARTS ON FOUR DIFFERENT SCALES.] The selection of suitable publication scales is of prime importance; a large scale permits of greater clearness and of showing more detail, but on the other hand restricts the area and the points that can be shown on a single sheet, or else makes a chart of excessive dimensions. In general in chart preparation the scale should be restricted to the minimum that can be used to fulfill the particular object and clearly represent what is desired. A chart of very large scale is not convenient for plotting, and a moving vessel may pass quickly beyond it or into range of objects beyond the limits of the chart. PUBLICATION OF CHARTS. #Methods of publication.# An ideal process of publication for nautical charts would include the following features; rapidity in getting out new charts, facility in reprinting and correcting existing charts, clearness and sharpness of print, durability of paper and print, and correctness of scale. It is difficult to fulfill all these requirements by any method as yet developed. In the Coast and Geodetic Survey several different processes are in use at present; charts are engraved on copper and printed directly from the copper plate, or they are transferred from the copper plate to stone and printed from the stone, or a finished drawing is made and transferred to stone by photolithography and printed from the stone, or an etching is made on copper from a finished drawing and printed from a transfer to stone. Charts in other countries are in large part printed from engraved plates, excepting some preliminary charts by lithography. [Illustration: FIG. 27. ENGRAVING A CHART ON A COPPER PLATE.] [Illustration: FIG. 28. ENGRAVING SOUNDINGS ON A COPPER PLATE WITH A MACHINE.]