Knowledge / Safety Measures / Watermarks / Changes

Watermark change: the same postage stamps issued chronologic with different watermarks
Watermark change: different postage stamps issued chronologic with the same watermark

Watermark introduction: the same postage stamps issued chronologic on paper without and than with watermark

Watermark omission: the same postage stamps issued chronologic on paper with and than without watermark

Watermark design change: the same postage stamps issued chronologic with different watermark designs

Edition 1890: without watermark
Edition 1906: watermark crosses and circles

Edition 1914: with watermark USPS
Edition 1916: without watermark

Edition 12.1920: lozenges
Edition 03.1922: network

Watermark kind change: the same postage stamps issued chronologic with the same watermark in different kinds

Watermark alignment change: the same postage stamps issued chronologic with the same watermark in different alignments

Watermark space change: the same postage stamps issued chronologic with the same watermark with different space between two parts

Edition 1901: single watermark
Edition 1904: multiple watermark

Edition 1881: vertical wavy lines
Edition 1888: horizontal wavy lines

Editions 1874 - 1897: 6 mm space
Editions 1902 - 1936: 2 mm space