Plate numbers for SG25
1 to 21
When the previous 16 perforation had been in use some eleven months, it was found defective in two respects : not only was too much paper cut away, thereby causing the stamps to become detached too readily, but the steel plates of the machines, into which the perforating pins descended, were found to be too weak, due in both cases to the close proximity of the holes. Consequently, in January, 1855, an alteration was made in the spacing of the pins, fourteen of which were introduced into the space previously occupied by sixteen. This allowed a greater body of metal between the holes in the plates, and, necessarily also, less paper was cut away in the process of perforating : thus the stamps, while readily severable from each other, were not so liable to be accidentally torn apart along the lines of perforation. The new gauge proving satisfactory, a similar alteration was made in all the perforating plates and pin-bars, the machines themselves remaining as before ; and the gauge of fourteen holes to the two centimetres became the standard, and—except for some of the larger-sized stamps.