Here is an item that may be of interest to readers of the Transvaal Philatelist.
The Machadodorp postcard is well known to us all and it has been described repeatedly over the years. The definitive work on this subject is the publication of Gerrit Jonkers and Joh Groenewald in 2006.
The item in the scan is a full-size publication and the postcard reverse. I have been puzzled for years as to what the full-size print actually was. I was under the impression the printing press on the train at Machadodorp could not do full size printings for some reason. I was wrong. The answer is in Jonkers and Groenewald p. 17 in the letter written by the printer at Machadodorp, A. Leys to Dr. WJ Leyds in Europe.
In the letter printer Leys described how he as printer had obtained permission from state secretary FW Reitz to print a miniature copy of “the first Staatscourant printed in the field” onto the back of a postcard. Leys (among others) also immediately bought a large number of the postcards for speculative purposes.
The image is the full size first Staatscourant nr. 1121 printed at Machadodorp and the well-known postcard is a copy in miniature of this document. The full-size copy and the postcard are an exact match in wording and appearance. A copy of the postcard is included for size perspective.
Reference: Jonkers, G. and Groenewald, J. (2006). Die Machadodorp-briefkaarte van die ABO. FFSA.