BLACK PROCESS COPYING.
This is accomplished by specially sensitized paper by which a fac-simile of the original drawing can be made; that is, black lines upon white ground. It also avoids the objection to the blue print paper of shaded drawings which show light and shade reversed.
The prints made by the process are said to be absolutely permanent and can be altered, added to or colored the same as original drawings.
The sensitized paper is sold ready for use, but it can be prepared by dissolving two ounces of citrate of iron and ammonium in eight ounces of soft water; keep in a dark bottle, also, one and one-third ounces of red prussiate of potash in eight ounces of water; keep in another dark bottle; when about to use mix an equal quantity of each in a cup and apply in a dark room with a soft brush or sponge to one side of white rag paper, similar to envelope paper, let it dry and put away in a dark place until required for use.
Drawing Office Rules.[1]
[1] Note.—A. W. Robinson, M.E., Montreal, must have all credit for these admirable rules and regulations. They bring into a single focus the whole science and art of mechanical drawing.
There are drawing offices where from ten to nearly one hundred people are busily employed in making new plans and sketches by the hundreds, and where thousands of completed drawings are filed for reference or for changes, as these are needed in the shop management.
To be introduced for the first time into such a company is a trial for the “new man” both of nerve and manners, and a test as well of skill; nothing helps more at such a time than an acquaintance with the rules and routine of the office, for the old saying holds good in a drawing office, of “doing in Rome as the Romans do.” The author of this book has felt this strangeness in a new position and so adds the following model-rules for the guidance of the student when first entering a regular position in an office where many are employed and where success depends upon a systematic ordering of the work in hand.