The ordinary type of tall pins or tacks used with wooden boards would not be at all satisfactory for this class of work, as it would be impossible to work with such boards containing thousands of tacks without knocking the tacks loose, so that they would be in a continuous process of becoming lost -- much to the detriment of accuracy and to the disgust of a cost clerk. The short glass-head pins pushed in until the heads touch are very convenient and they give a thoroughly accurate record.

As above mentioned, cost boards of the kind described would not be satisfactory if made with ink dots because the boards would soon have so many dots that information would be no longer easily obtainable. By using the glass-head pins it is feasible to change the color of glass heads used on any board each six months. The position of the pins of different color would then show clearly whether work was being done more cheaply than it had been done in preceding periods of time. Thus, if any particular campaign were made to reduce the cost for small orders by handling small orders on some different method from that previously used, the pins near the left-hand side of the board might appear considerably lower down on the chart than the pins of the color which had been used in the six months preceding the change in method.

When the board gets so full of pins as to make the pins crowded it is a very simple matter to remove from the board all of the pins which Avere inserted in the most remote period of time. Thus, it might be