chronology. No G, H, I or J grills are found on the 1861-68 issue, for this series went out of production before they were introduced. The 1869 issue used only the G grill, while the 1870 issue used H and I grills. Fears of reuse had abated by the early 1870s, and grilling seems to have been quietly dropped from the production process. Some stamps of the Continental Bank Note Company (who took over production from National) are known to have been impressed with the "J" grill as late as 1875. Grills: A Grill - overall (first experimental grill) C Grill - points up, 16-17 x 18-21 points (second experimental) Z Grill - points down, points with horizontal ridges, 13-14 x 17-18 points D Grill - points down, vertical ridges, 15 x 17-18 points E Grill - points down, vertical or "X" ridges, 14 x 15-17 points F Grill - points down, vertical or "X" ridges, 11-12 x 15-17 points B Grill - points up, "X" ridges, 22 x 18 points G Grill - points down, vertical ridges, 12 x 11-11.5 points H Grill - points down, vertical ridges, 11-13 x 14-16 points I Grill - points down, vertical ridges, 10-11 x 10-13 points J Grill - points down, vertical ridges, 9-10 x 12 points The least-widely used of these patterns (all associated with the 1861-68 issue) were the "B" and "C" Grills (both found on only the three-cent denomination), the "D" Grill (found only on the two-cent and three-cent denomination) and the "A" Grill (found only on the three-cent, five-cent and thirty-cent denominations). The rarest grilled U. S. stamps are: thirty-cent I Grill (1 surviving copy—see note below) one-cent Z Grill (2 surviving copies) fifteen-cent Z Grill (2 surviving copies) twelve-cent I Grill (2 surviving copies—see note below) ninety-cent I Grill (3 surviving copies—see note below) three-cent B Grill (4 surviving copies) five-cent A Grill (4 surviving copies) ten-cent Z Grill (6 surviving copies) thirty-cent A Grill (8 surviving copies) Note: Given that intensive studies of the I Grill began only recently, additional copies of the I Grill issues listed here may well be discovered in the future. Because certain grill patterns were only belatedly recognized as features of separate collectible stamp issues, not every U. S. grilled stamp was assigned its own individual numeral in the standard Scott catalogue. Issues that share numerals are as follows: 3-cent D