Page:Popular Science Monthly Volume 88.djvu/660

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A Self-Rocking Developing-Tray

A SIMPLE form of mechanical rocker, which may be relied upon to keep up a steady, gentle movement for a long period without attention, is a great convenience to the busy photo- grapher. A flat, square board, rather larger than the developing - tray, is pivoted on the apex of a zinc triangle, as shown in Fig. I. The zinc triangle is easily made from a strip of sheet zinc

��FIG. I

��Popular Science Monthly

���The counterbalance swings under the

table and the tray rocks easily and

continuously without attention

as long as the side of the board and bent into the form of a V, with flanges for attachment to the board. It should be screwed along the exact center of the under side. An alternative is to use a triangularly-shaped piece of wood, IV^'^ thick, nailed through from above. The wood must, of course, be rather hard. A piece of strong, flat iron, 3' or more in length, must be fastened at one end to the under side of the base, also in the center, but at right angles to the pivot. This is shown in Fig. II.

With the board standing on the edge of the table, the iron should be bent into a curve reaching under the edge of the table as illustrated. A weight of several pounds is firmly secured to the free end of the iron. This weight can be made by casting ten or twelve pounds of lead scrap into the shape of a disk, a hole being made through the center for bolt- ing the disk to the arm. The disk weight must be fastened securely ; else the movement will be jerky, and much energy will be lost. In bending the iron, it will be necessary to adjust it by degrees until the board is found to bal- ance freely on the pivot and come to rest in a level position.

The rocker leaves the operator free to attend to other matters while develop- ment is proceeding. If it is desired to

��open the darkroom door, a sheet of card- board should be laid on the dish, and a light-proof cover should be placed in posi- tion. A cardboard box slightly smaller than the board, makes a good cover, if lined with two thicknesses of black twill, with additional pieces at the corners. This rocking arrangement is a time-saver for any photographer.

A Whole Tool-Box in One Tool

THE day of the family tool-box may soon be a matter of past history if a device that is now on the market can do all that its manufacturers claim for it. The tool that threatens to do this revolutionizing is 10 inches in length and weighs 11 ounces. It can do every- thing that a variety of household tools can do and other things besides. Here are a few of the tools whose work it intends to accomplish: Hammer, lifter for hot pans and dishes, tack-puller, screwdriver, nut-cracker, box-opener, wrench, pliers, rule, measure and ice- chipper. It works automatically.

���This "Jack-of-all-tools" may be used to

lift a hot plate off the stove or to hammer

the tacks in the parlor carpet

FULLY one-half of all the automo- biles sold in the United States are bought by farmers and others living in rural communities.

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