Hiram Maxim is obviously best known for the Maxim Machine Gun, but he and (most significantly) his assistant Louis Silverman also dabbled in handgun design. It appears that the work was primarily Silverman’s, done with the tacit support of the Maxim company. A followup version was made with more of Maxim’s fingerprints on the design, but it never appears to have been produced – while three of the Maxim-Silverman guns are known to still exist.
This pistol began as a simple blowback action, albeit a clever and elegant one. It was chambered for the 7.63mm Borchardt cartridge, which proved to be too strong for a blowback mechanism to safely handle. This was remediated by the addition of a delaying spring added to the side of the frame to hold the bolt closed slightly longer during the firing process. The two other known prototype examples are in different calibers; one in an experimental 8mm version of the Borchardt round, a larger framed model in .455 Webley.
Overall, these pistols are simple, elegant, and quite ahead of their time. It is unfortunately that they were not given more attention at the time, but it is reasonable that the Maxim company would be more interested in devoting its resources to the military machine gun market.
Thanks to the Institute of Military Technology for giving me access to this pistol!