Norman Shachat led the seminar for April, with a fascinating talk on the octagonal postmarks of Philadelphia. Norm noted how these postmarks are only found in the period 1834 to 1836. He showed examples of each of the different varieties of these markings, including covers that were forwarded to other destinations. He also showed examples of ancillary octagonal markings, including free, paid, forwarded and a six cent rate marking. Among the highlights of the collection were an example of the Philadelphia full-rigged ship marking in red and one of the extremely rare (only 20 known) copies of the Northern Liberties News Room Sub Post Office marking. This wood-engraved marking was used between 1835 and 1836, and was printed in black on lettersheets.