��Popular Science Monthly
���Diagram of a Drill About 3 Inches in Length for Drilling Plate Glass
Making a Plate-Glass Drill
THE accompanying diagram shows a drill about 3 ins. in length for tlu- drilling of plate-glass. It can be made from an old corner-file. It allows for the drilling of any size hole, which depends on the size of file and the length and size of taper.
The piece of file is ground down along its side on a taper until a point concen- tric with sides of the file is obtained. The point should then be cut off obliquely, as shown in the illustration. It is then ready for use. Drills of this kind can be used for many years with satisfactory results. — John Havkkost.
Coloring of Copper
COPPER and bra.ss lend themselves readily to a coloring process and may be worked to all shades and hues imaginable by merely oxidizing the surface of the metal. Make a paste of iron oxide and graphite with wood alcohol or with plain water, and apply this to the article, which is then hcateil in an oven or over a suitable gas flame. It is belter to use alcohol as it dries out much quicker. The color obtained will depend on the amount of iron oxide mi.xed with the graphite and the length of time that the heat was maintainetl. The more oxide in the coating the darker the shade will be. The remains of the coating shfuild I)e remoxed with a brush or cloth moistened in alcohol, and when the surface has become quite clean the color should be ])rotected by ap|)l\ ing varnish, la((|iuT or pure \\ax, wliicli may be laid on with a brush while the copper is heated.
Some brown colors are obtainefl by
��using a mixture of verdigris, sal ammoni- ac and \inegar, using two or three times as much verdigris and sal ammoniac as vinegar. The color or shade can be rendered much darker by adding some blue \itriol to the s<^jlution. A red brown may be given b\' using a vinegar paste, containing equal parts of verdigris and cinnabar, together with two and one-half times as much each of sal ammoniac and alum. The heat treat- ment is the same as for the other coatings. A wide range of colors comprising shades from blue-black to blue-gray may be given to the copper by dipjiing it in a hot "liver of sulphur" solution, then washing thoroughly, re- dipping, or scratch-ltrushing, and again dipping and washing if desired.
A Handy Spacing Scheme
THE drawing illustrates a handy .scheme for drawing parallel lines spaced accurately at equal distances.
Take a strip of ruled paper and fasten it where\-er you choose on the drawing- board. The ruled lines on the strip are used for guides cither for the T-square or for triangles. The strip may be fastened vertically on the board, hori- zontally, or at any angle.
In case of absence of ruled quadrangle paper, advertisement borders do very well. I have used the "spaced variety" of advertisement border successfully many times. It will be found in various spacings. — N. G. Ne.vr.
���Ruled Lines on the Strip Are Used for Guides for T-squarc or Triangles