Scott #1622 depicts a 13-star flag over Independence hall. This issue is perforated 11 by 10.75. It is a very common stamp with the typical minimum catalog value of 20˘. These stamps were line perforated. That is, rows of perforating pins would perforate the stamps in one direction. Then the sheet was turned so that another row of perforating pins would perforate the stamps in the second direction. Where the rows of pins meet at the corners of the stamp, the holes do not intersect perfectly. The holes are misaligned and you end up with an oblong looking hole.
A lesser known cousin, Scott #1622C, is perforated 11.25. A mint or used single catalogs 20˘ too. This stamp has bullseye perforations. These stamps were perforated in both directions at the same time. The corners of the stamp show a perfectly aligned, single perforation hole (hence, the term “bullseye”).
Identification of single stamps requires a perforation gauge. However, identification of blocks or panes of stamps is quite easy. Scott #1622 shows an imperfect intersection of perforation holes at the four corners of each stamp. Scott #1622C shows a single perforation hole in each corner.
Plate blocks of #1622 and #1622C are collected as a plate number strip/20 due to the floating plate numbers. Plate blocks of Scott #1622 are common and sell for about $6. Plate blocks of #1622 are always horizontally oriented. Plate blocks of Scott #1622C are uncommon and sell in the $30-$40 range. Plate blocks of #1622C are always vertically oriented.
When buying mint, discount postage, keep an eye out for any copies of #1622C. Sometimes you’ll find plate blocks of #1622C in these accumulations. Some people don’t realize they have the more scarce #1622C variety and they throw it in with other inexpensive mint stamps.
Single copies of either stamp are inexpensive. However, plate block collectors didn’t pick up on the differences in perforation and many missed out in obtaining a plate block of #1622C. Keep your eyes open. You may get lucky and find a more valuable plate block. Good luck!