What did I do with myself during that six months? Well, I was not altogether idle. First I found all the drawers in the drawing-office filled with piles of old drawings which Mr. Merrick ordered to be preserved and which we piled up on the floor of the unoccupied third story. Out of the contemplation of that confused heap I evolved a new system of making and keeping mechanical drawings, which I described in the following paper, read the next year before the American Society of Mechanical Engineers: “The system of making and keeping drawings now in use at the works of the Southwark Foundry and Machine Company in Philadelphia has been found so satisfactory in its operation that it seems worthy of being communicated to the profession. “The method in common use is to devote a separate drawer to the drawings of each machine or each group or class of machines. The idea of this system is keeping together all drawings relating to the same subject-matter. Every draftsman is acquainted with its practical working. It is necessary to make the drawing of a machine and of its separate parts on sheets of different sizes. The drawer in which all these are kept must be large enough to accommodate the largest sheets. The smaller ones cannot be located in the drawer, and as these find their way to one side or to the back, and several of the smallest lie side by side in one course, any arrangement of the sheets in the drawer is out of the question. “The operation of finding a drawing consists in turning the contents of the drawer all up until it is discovered. In this way the smaller sheets get out of sight or doubled up, and the larger ones are torn. No amount of care can prevent confusion. “In the system now proposed the idea of keeping together drawings relating to the same machine, or of classifying them according to subjects in any way, is abandoned, and in place of it is substituted the plan of keeping together all drawings that are made on sheets of the same size, without regard to the subject of them. Nine sizes of sheets were settled upon as sufficient to meet our requirements, and on a sheet that will trim to one of these sizes every drawing must be made. They are distinguished by the first nine letters of the alphabet. Size A is the antiquarian sheet trimmed, and the smaller sizes will cut from this sheet, without waste, as follows: “A, 51″×30″; B, 37″×30″; C, 25″×30″; D, 17″×30″; E, 12¹⁄₂″×30″; F, 8¹⁄₂″×30″; G, 17″×15″; H, 8¹⁄₂″×15″; I, 14″×25″. “The drawers for the different sizes are made 1 inch longer and wider than the sheets they are to contain, and are lettered as above. The drawers of the same size are distinguished by a numeral prefixed to the letter. The back part of each drawer is covered for a width of from 6 to 10 inches, to prevent drawings, and especially tracings, from slipping over at the back.