by Milton and Wohlers; 1919

PLATES a , a’. SINGLE SPIRAL. STRAIGHT SHAFT To work out a single spiral for a pedestal proceed as follows: 1. Turn a cylinder 2¼" in diameter. Make the ends slightly larger in order that the design may be turned on each, after the spiral has been worked out. |

2. Lay off spaces 2-1/16" apart on the cylinder while the spindle is turning in the lathe and divide each of these into four equal parts. Each one of these large spaces represents one turn of the spiral. A good proportion is slightly less than the diameter of the cylinder; thus the diameter of the cylinder equals 2¼" and the width of the space 2-1/16".

3. On the cylinder parallel to the axis draw lines A-A B-B C-C D-D. These lines should be 90° apart as shown in the top diagram (Plate a’). Line D-D is on the other side of the cylinder as shown in the top and middle diagrams.

**Fig. 23.**