There Are Many Kinds of Stamps : Page 25

a very considerable sum. In the case of the Pombalssries issued by Portugal in 1925 an extremely ingeniousidea was employed. With this issue it was made manda-tory that on certain specified days the Pombal stampswere required in addition to ordinary postage stamps.Failure to use them resulted in "postage due" beingcharged and for this purpose special Pombal postage-duestamps were issued. The money thus raised was to beused to build a national monument to the Marquess ofPombal. In this case the entire population of the countrywas directly taxed. Also, of course, many hundreds ofthousands of the stamps were acquired by collectors.