The mechanic Otto Büttner from Dresden constructed this very well-built early pinwheel machine. Its German patent (No. 47243) is dated 7. November 1888, but Büttner and his business partner Wilhelm Brückner could not achieve series production of this machine. One immediately notes its elongated shape and the lever for changing from addition to subtraction or from multiplication to division. These were the typical attributes of the common Thomas stepped drum machines, but this machine works with Odhner’s pinwheel principle (German patent No. 7393 dated 1878). Thus Büttner did not choose to incorporate the main advantages of a pinwheel machine as found in Odhner’s machines that appeared on the market towards the end of the 1880s, namely its compact form and its simple usage with the bidirectional crank. This anachronism, combined with its far too complicated construction, probably accounts for Büttner’s business failure. But as late as 1902 he bought the company shares owned by Brückner’s widow (cf. handwritten document). The machine must have been available in several sizes up to at least 1892. According to Dyck [1892] the 6-place one cost 325 M, the 8-place one 425 M and the 10-place one 625 M. These machines were thus somewhat cheaper than the corresponding Burckhardt stepped drum machines. The Arithmeum machine with the machine No. 90 is the one that Büttner had demonstrated to the Royal Saxon Ministry of the Interior in Dresden in 1889 (cf. certificate depicted in the user’s manual).