In the absence of a waste nut, an iron pipe can be easily fastened to sheet-metal work as shown in the sketch. The end of the pipe, Fig. 1, is slotted with a hacksaw to form four projections, which are turned outward consists of two horizontal strips joined at the ends with grooved pieces, fitting the edge of the new back, so that it may be slid up and down in the grooves. The crosspieces are also rabbeted to receive the reversible back and allow it to be moved back and forth horizontally. The rabbet in the horizontal strips should not be so deep as to permit the extending edge to overlap the ground-glass frame, thus preventing it from moving back as the plate holder is inserted.

The End of the Pipe as It is Prepared to be Riveted on the Sheet Metal

Ill: The End of the Pipe as It is Prepared to be Riveted on the Sheet Metal

If the frame on the back and the reversible back fit tightly, they will remain in any position, but if they are loosely fitted, it will be necessary to provide some means to hold them. Small springs with pins may be fitted to the vertically moving frame to hold it in the position for the horizontal rows of pictures.

The ground glass should be marked for the size picture to be taken. The positions of the frame and plate carrier should also be marked so that the plate holder need not be taken out to find the location and focus for the next picture.

and their ends rounded as shown in Fig. 2. The face of the projections are tinned and then riveted to the sheet-metal surface, as shown in Fig. 3. After soldering the joint, it will be as good or better than if a waste nut had been used. - Contributed by Lorin A. Brown, Washington, D. C.