For the stamps of St. Vincent three varieties of perforating machines have been used by Messrs. De La Rue & Co. First, a comb-machine of the gauge of 14, similar to the one they employ for perforating the current One Penny &c. of Great Britain, in which the horizontal line of pins is long enough, without the interposition of two vertical lines placed close together, to perforate a row of ten or more stamps; second, a single-line or guillotine-machine with 12 holes in a space of 2 centimetres; and third, a similarly constructed machine to the second, but with a gauge of 14. In order to distinguish between the perforations of the guillotine-machine gauging 14 and those of the comb-machine which also gauges 14, it is necessary to have either a block of at least four stamps, or a vertical strip with the top and bottom margins of the sheet attached. By examining the points where the lines of perforation intersect each other, or noticing whether _both_ margins of the sheet have been perforated through or not, it is possible to decide the nature of the machine. If, at the point where a vertical and a horizontal line of perforation intersect, there is one hole common to both lines, this hole being of the usual size, or if either the top or bottom margin of the sheet is imperforate, then the perforation must have been done by the comb-machine. On the other hand, if the lines of perforation cross each other so that there is no one hole common to both lines, or if there appears to be such a one that it has evidently been made larger by the passage of a second pin, or if the top and bottom margins of the sheet are _both_ perforated through, then we may be equally certain that the perforation has been performed by the guillotine-machine. The comb-machine perforating 14 is far more regular in the spacing of the pins than the guillotine-machine of the same gauge. If a long line of perforation of the latter be examined, it will be found that here and there the holes are not in line, and also that there is a slightly wider distance between certain of them, although the gauge of the perforation does not perceptibly vary from 14. The guillotine-machine gauging 12 is more irregular still in the spacing of the pins, as an examination of our illustration No. 21 will show. For instance, the tenth hole from the bottom is further from the ninth than it is from the eleventh, and the second and third holes from the top, and also others, will be seen to be more or less out of line. The gauge also varies; for if two centimetres be taken up the central line, commencing with the fifteenth hole from the bottom, that space will be found to contain eleven holes, _plus_ the distance between the eleventh and twelfth, which is equivalent to a gauge of 11¾.