Paragraph 3. With your try-square blade (which is perfectly straight) held in the position shown in Figure 14, you may test the surface to make sure that it is even. Push the square along the entire surface of the board carefully, watching to see that it fits closely upon the surface all the way across and that light cannot shine under it at any point. When the edge of the square blade will touch every point on the surface of the board as it passes, the working face is prepared. Mark this face with the letter "X," for you will want to refer to it from time to time in handling this piece of material.

Figure 14.