If a belt is to be carried from a pulley on an overhead shaft to one on any floor above, the distance from centre of lower shaft to ceiling-under side of floor-should be measured and noted; then the thickness of floor; next the distance between top of floor and centre of upper shaft. If one pulley or shaft is directly over the other, the size of pulleys and width of belt being known, you have all the data necessary if you measure the distance of one shaft from the wall of building, which is done by dropping a plummet from centre of shaft or diameter of pulley, and measuring to the wall from that point. From these data, whether the two shafts are in the same vertical plane, whether the diameters of the pulleys are equal, and whether the belt is to be carried through one, two, three, or even four floors or not, the intelligent mechanic can lay out a diagram that will enable him to cut his belt-holes accurately. The diagram may be laid out full-size on a swept floor, or, on a reduced scale, on a board or sheet of paper. Measures thus made can easily be transferred to the floor through which the holes are to be made.