is laid upon the board, which it somewhat overlaps, and the frame then comes down and turns over the edges of the paper upon the sides of the board, and the frame being then fixed so that its face is flush with the paper, the paper by being thus bound all round the edges is properly stretched when dry. In Mr. Watt's time the drawings were made with copying ink, and an impression was taken from them by passing them through a roller press, so as to retain the original in the office, while a duplicate of it was sent out with the work; and the copying press was invented by Mr. Watt for this purpose. The whole of the drawings pertaining to each particular engine are placed in a small paper portfolio by themselves; and these small portfolios are numbered and arranged in drawers, with a catalogue to tell the particular engine delineated in the drawings of each portfolio. In this way I have found that the drawings illustra tive of any engine, though it may have been made in the last EXAMPLES OF APPROVED DIMENSIONS. PARTS OF MESSRS. SEAWARD AND Co.'s MARINE century, could be produced to me in a few minutes; and the system is altogether more perfect and more convenient than any other with which I am acquainted. The portfolios are not large, which would make them inconvenient, but are of such size that a double elephant sheet has to be folded to go into one of them; but most of the drawings are on small sheets of paper, which is a much more convenient practice than that of drawing the details upon large sheets. It will be interesting to compare with the results given in the foregoing rules the actual sizes of some side lever engines of approved construction. Accordingly I have recapitulated, in the tables introduced above, the principal dimensions of the marine engines of Messrs. Maudslay and Messrs. Seaward. These tables are so clear, that they do not require further explanation, and the same remark is applicable to the tables which follow. 293 Diameter of Cylinder in inches. DIAMETER OF WROUGHT-IRON CRANK-SHAFT JOURNAL. 9.65 10-15 10.62 11.04 9-80 10-31 10.78 11-21 9.65 9.95 10-47 10.95 1138 9-79 10-10 10-63 11.11 11.55 9.94 10-25 10.78 11-28 11-72 9.55 9-92 10.23 10-54 11.09 11-61 12.06 9.46 9.82 10-20 10:51 10.84 11:42 11.94 12:41 9-71 10-08 10:47 10.79 11-12 11-71 12.25 12.73 9.50 54 7.90 8.52 9.05 56 8.09 8.73 9.27 69 62 8.67 9.35 9.96 10-34 10.74 11.06 11-40 12.00 12.56 13:05 9.73 10-21 10.60 11-01 11:33 11.69 12-29 12.87 13:37 58 8.29 8.94 9.50 9-97 10-45 10.86 11.28 11.61 11.97 12:58 13-18 13-69 8:49 9.15 9.72 10-20 10-70 11-12 11:55 11.89 12-25 12.89 13:48 14.02 9-93 10-40 10.89 11:34 11-79 12-14 12-51 13.17 13.77 14:32 64 8.86 9-55 10-14 10.60 11.08 11.56 12.03 12:39 12-78 13:45 14:06 14-62 66 9.04 9-74 10-35 10-79 11-27 11.78 12-28 12.64 13.04 13.73 1435 14.93 68 9.22 9-94 10 56 10-99 11:45 11.99 12:52 12.89 13-30 14:01 14.64 15-23 70 9-41 10-14 10-77 11-19 11-64 12.20 12.77 13.16 13:57 14-29 14.94 1554 72 9.59 10-33 10-97 11-41 11.90 12-44 13.01 13:40 13.82 14:55 15-22 15.83 74 9.76 10.52 11.17 11-62 12-16 12.67 13.25 13.64 14.07. 14.82 15.50 16-12 76 9-93 10.71 11:36 11.83 12:43 12.91 13-49 13.89 14:32 15.09 15.78 16.41 78 10.11 10.89 11.56 12.05 12.69 13:15 13.73 14.13 14:57 15-35 16:06 16-70 80 10-29 11-08 11-76 12-27 12.96 13:38 13.96 14:38 14.84 15.62 16:33 16.98 82 10-46 11-26 11.96 12:49 13.17 13.61 14-19 14-62 15.08 15.88 16:59 17-26 84 10.63 11-44 12-15 12-71 13-38 13.84 14.42 14.85 15.32 16-13 16.86 17:54 86 10.80 11.61 12:35 12.92 13:59 14:07 14.65 15.09 15.56 16:38 17-13 17:52 88 10-97 11-79 12:54 13-14 13.80 14:30 14.88 15:32 15.80 16.63 17:40 18-10 90 11-13 11.99 12-74 13:34 14:00 14:54 15:10 15:56 16-05 16:59 17.66 18:37 92 11-29 12-17 12.92 13-47 14-21 14.75 15:32 15.79 16-28 17:14 17.92 18-64 94 11:45 12:34 13.10 13.60 14:42 14.96 15.54 16.02 16.51 1738 18 18 18.91 96 11.61 12-51 13.29 13.73 14.63 15-18 15.76 16-25 16.74 17.63 18:44 19:18 98 11 77 12-68 13.47 13.86 14.84 15:39 15.98 16:48 16.97 17-87 18-70 19:45 100 11-93 12-85 13-66 14.01 15.04 15.61 16-20 16.71 17-22 18-12 18-95 19-71 |