Various authors

“ Method of Setting Dividers Accurately
Combination Caliper and Divider
The combination caliper and divider shown in Fig. 15 is one that is not manufactured by any of the various tool companies. It is, however, one of the handiest tools that can be in a machinist's kit, as it lends itself to so many varied uses, and often is capable of being used where only a special tool can be employed. The illustration suggests its usefulness. The tool can be used as an outside caliper, as an inside caliper, and as a divider. ”

“ Fig. 4 shows a method of setting the calipers by using a small square to abut the scale and to afford a surface against which to place the leg of the caliper. The scale, lying flat on the blade of the square, is always sure to be square edgewise, and is easily held squarely against the stock of the square as shown. This method has also the advantage of being portable, and can be taken to the window or to any place where the light is satisfactory. When using a long scale, the free end may be held against the body to assist in holding it in place. [1]
Shoulder Calipers
Fig. ”

“ The common form of this tool has generally only one toe on the caliper legs, but the double toes save the reversal of the points when changing from outside to inside work. The divider points may be set at an angle, which permits of stepping off readily around the outside of a shaft at angular distances, where the ordinary dividers are useless. A number of other uses could be mentioned, but any intelligent mechanic can readily suggest them for himself.
Fig. 15. ”