L. Wesley's "Air Pistols and Air Rifles"

Or may be "Dennis E. Hiller's Collector's guide to Air Pistols" - text and photo is absolutely identical.

Maker:  Em-Ge, trade name of Moritz & Gerstenberger. Zella-Mehlis, Thuringia, Germany. (Formerly Eastern Germany).
Date:  Design patented in 1937 and outbreak of War in 1939 means a very short period of production. Many writers give the impression that the Zenit is common, but in my experience it is not. Would suggest that the production was very short, only about three years. Some of these may have appeared after the War from the Russian sector of Germany, but this seems most unlikely.
Valuation:  £40 - £70.
Details:   The predecessor of the Diana Model 4. Top strap lifts up and is raised over the end of the airpistol in order to cock the action. Fitted with an intercepting sear so that action must be fired when cocked. Top strap is stamped "PATENT" on side and on one example seen was stamped with a silhouette of a twin funnelled ship with "GERMANY" inside. Top of strap marked and ZELLA-MEHLIS (THUR). From tip of barrel in -177 only, rifled or smooth bore. Steel barrel had a brassliner. Barrel stamped "CAL. 4.5m/m (-177)".
     Some barrels had "gez" after the calibre, this indicates a rifled bore. The foresight was adjustable for both windage and elevation, this is accomplished by unscrewing the only one on the sight. It can then be either turned to the right or left for windage or the foresight blade can be highered or lowered for elevation. There are graduation marks on the barrel and blade to mark degree of adjustment. The barrel is spring tensioned so that as soon as the top catch is raised the barrel immediately tips down for loading. The rear chamber plug is a bayonet fit and can easily be removed by pushing in and turning.
     The cocking linkages are pivoted by pins whereas on the post-war British models screws were wisely used. One-piece hardwood butt with EM-GE medallions on each side The rearsight is formed by upturned metal of the top loading catch, and has a "U" cut into it. The Patent for the above design was number 472021, dated 1937 so manufacture could have started in the same year.
     Would assume that it was only made for about three years at the most so contrary to what other books state the above is quite a rare airpistol. It was also made in a repeater version, but this is rarely encountered. The butt has pressed chequering. The patent was made by Franz Moller of 10 Rathaus Strasse, Zella-Mehlis, Thuringia, Germany and his British agent for the patent was A. P. Thurston, 329 High Holborn, London.
     The Patent was for the novel design of the above and the top cocking lever. The end cap can have the annoying habit of flying off and hitting the user full in the face; the Author, when using the above, kept his thumb over the end cap as the thought of the pellet coming from the front and the mainspring, guide and cap proceeding from the rear was just too much to bear.
     Apart from the above ship-like trademark another type of marking seen is "PATENT ANG-GERMANY".

The Zenit airpistol.

Source scan of page with Zenit air-pistol.