Fig. 138. paper along the edge of the ruler. Be sure to have the ruler precisely at the corners; if placed either to one side or the other, the centre will not be found. Fig. 138 shows the first line drawn; cross this line by another running from the remaining two corners which will give Fig. 139; the point where the lines intersect is the exact centre of the picture. Cut the mounting board in portions large enough to allow a surrounding margin of four or five inches
Fig. 139. on each picture; then mark the centres on the right, not wrong, side of the mounting board. It will be unnecessary to extend the line from corner to corner of the mounting board; lay the ruler across and mark it merely at the centre, Fig. 140. Take the print
Fig. 140. you intend to mount first and carefully place it upon the blank piece of paper so that the centre of the picture will be exactly over the centre of the blank paper; lightly mark a line in lead-pencil around two corners of the picture, remove the print and the blank paper resembles Fig. 141. The last markings are a guide in pasting the picture on the sheet of paper. First dampen the wrong side of the print with a wet sponge. Have ready some strong paste and spread it lightly on the wrong side. Be careful not to get too much paste lest it smear the mounting-paper. Lay
Fig. 141. the mounting-sheet upon a perfectly clean, level surface and place the print on it according to the guiding marks. Have the picture absolutely smooth, without a suspicion of a wrinkle or blister, and with a clean cloth again smooth it gently, pressing it down here
Fig. 142. and there as seems necessary to make it adhere firmly (Fig. 142). Then place a weight upon the mounted picture and leave it to dry. After having been successful with one picture no difficulty will be found in mounting the others.