“The introduction of the blue-printing process has revolutionized the drawing-office. Our drawings now are studies, left in pencil. When we can find nothing more to alter, tracings are made on cloth. These become our originals and are kept in a fire-proof vault. _This system is found admirably adapted to the plan of making a separate drawing for each piece._ The whole combined drawing is not generally traced, but the separate pieces are picked out from it. _All our working drawings are blue-prints of separate pieces._ “Each drawer contains fifty tracings. They are 2¹⁄₂ inches deep, which is enough to hold several times as many, but this number is all that is convenient to keep together. Each drawing is marked in stencil on the margin in the lower right-hand corner, and also with inverted plates in the upper left-hand corner, with the letter of the drawer and the number of the drawing, as, for example, 3F-31; so that whichever way the sheet is put in the drawer, this appears at the front right-hand corner. The drawings in each drawer are numbered separately, fifty being thus the highest number used. “For reference we depend on our indices. Each tracing when completed is entered under its letter in the numerical index, and is given the next consecutive number. From this index the title and the number are copied into other indices, under as many different headings as possible. Thus all the drawings of any engine, or tool, or machine whatever, become assembled in the index by their titles under the heading of such particular engine or tool or machine. So also the drawings of any particular piece, of all sizes and styles, become assembled by their titles under the name of such piece. However numerous the drawings, and however great the variety of their subjects, the location of any one is, by this means, found as readily as a word in a dictionary. The stencil marks copy, of course, on the blue-prints, and these, when not in use, are kept in the same manner as the tracings, except that only twenty-five are placed in one drawer. “We employ printed classified lists of the separate pieces constituting every steam-engine, the manufacture of which is the sole business of these works, and on these, against the name of every piece, is given the drawer and number of the drawing on which it is represented. The office copies of these lists afford an additional mode of reference, and a very convenient one, used in practice almost exclusively. The foreman sends for the prints by the stencil marks, and these are thus got directly without reference to any index. They are charged in the same way, and reference to the numerical index gives the title of any missing print.