What are the instructions for work № 19?

Instructions for work № 19:

• 1. In accordance with the recommendations given in § 37, complete the drawings of the following parts:
• 1) drawing 240, parts 2, 4;
• 2) drawing 244, parts 1, 3;
• 3) drawing 245, parts 2, 3;
• 4) drawing 246, parts 3, 4;
• 5) drawing 247, parts 1, 2;
• 6) drawing 248, parts 1, 3.
• 2. To determine the dimensions of the parts, a proportional scale can be used (fig. 258). For example, in figure 254, the distance between the centers of the holes is 45 mm. Lay this value on a horizontal line. From the end of the segment, draw a perpendicular. On it, from the vertex of the angle, lay the distance between the centers of the holes, but taken from the drawing in the book. Connect the ends of the segments with a straight line (in the figure, it is shown in a different color).
• To determine the size of any segment on this drawing, lay this segment from the vertex on the vertical side of the angle and draw a line parallel to the previously constructed line. It will mark the actual size of the segment being determined on the horizontal side of the angle.