 This issue was first overprinted by Mr. C. Bertoncini who was the Chief of the Canal Zone Division of Map Making, and then transferred to the Printing Bureau of the Engineering Department, also known as the 'Commission Printing Office', in August 1905.The Third Series is very interesting because of the myriad combinations in the overprints.The Canal Zone Director of Posts, sent a memorandum to all postmasters instructing them to sell these stamps for their face value in gold, or in Colombian silver at the rate of two for one.