This, as shown in the illustration, consists of a square-bottomed bos, the tops of the sides of which are inclined like those of a writing-desk. The back is open, and, as the apparatus rests on the table, abuts against a window. The window-shade is drawn down to meet the upper part of the device, so that the light enters through the back of the latter, and the interior, being lined with white paper, is reflected up through the inclined glass top; the original drawing is laid upon the glass, and a sheet of tissue-paper ruled off in squares is placed above it. Being brilliantly illuminated from below, the drawing would readily show through, and might be copied, square by square, as before described.

A Transparent Tracing-Table