In this manner it is possible to tell blocks and pairs of this perforation without any side margins. Single copies perforated in this manner can occasionally be detected by the distance between the vertical perforations. In the later perforation of this issue the distance is fixed (as will be shewn), and the distance is 20 1/2mm., [page 30] measuring from perf. point to perf. point across the stamp. Any stamp differing in width to any extent more than 1/2mm. from 20 1/2mm. may therefore be set down as perforated by the single line machine. We have seen all the values except the 2d. rose and 1/- green perforated by the single line machine, in practically every case the C.C. watermark being upright, the exception being a strip of three 6d. with the sideways watermark. All the sheets with this perforation appear to have one printer's guide dot in the centre of each side margin. The next form of perforating machine introduced in later printings of the Crown and C.C. 1880 issue is known as a comb machine. The comb machine perforates three sides of a stamp at once, and the form of the first comb machine was arranged thus-- ............................................................... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : The arrangement of the teeth of the comb fitted the arrangement of the panes of the regular Colonial postage stamps printed by Messrs. De la Rue & Co., the narrow spaced teeth in the centre marking the dividing space between two horizontal panes. In perforating the stamps of Gambia in the small sheets of fifteen in three horizontal rows of five, both sides of the machine appear to have been used, the extreme end portion of the comb at either end running off the side margin of the small sheet. When the left portion of the machine was being used the sheet was [page 33] inserted upright and the top row of stamps perforated first, the effect being that the top margin is not cut through by vertical perforations, and the bottom row is (see plate III.). When the right-hand portion was in use the sheets appear to have been systematically inverted when placed in the machine. This left the bottom margin blank and the top margin cut through. Had the sheet been simply inverted and perforated by the same portion of the machine, as already described, the narrow spaced teeth would have been produced on the left hand margin instead of the right. A comparison of plates III. and VI. will shew that the narrow spacing is on the right in both cases, but in III. the perforating has been started at the top on the left side of the machine, and in VI. from the bottom on the right side of the machine.