Esser

When the firm Grimme, Natalis & Co. in Brunswick began producing the pinwheel machine Brunsviga in 1892, the mechanical engineer Heinrich Esser from Aachen obtained the German patent No. 82 965 for his machine, which also used pinwheels. In the introduction of his patent document Esser listed three particularly advantageous features of his machine: the convenient setting mechanism, the reliable tens-carry in the result mechanism which he attributes to the setting mechanism, and the tens-carry in the revolution counter, the so-called divisor counter. The two extant machines of this construction (one in the Brunswick State Museum with capacity 6 x 8 x 14, the other in the Arithmeum with capacity 7 x 8 x 15) indeed have a more reliable setting mechanism than the Brunsviga as the setting levers are better placed and have well defined positions, and there are windows showing the number entered. Both machines, however, have no tens-carry in the revolution counter, so that the short multiplication described in the patent document cannot be performed. The tens-carry mechanism in the Esser machine differs from that of the Odhner machine in that a simple-looking lever construction pushes the spring-loaded tens-carry cogs out of the pinwheel, into which they return after the tens-carry step is completed. The crank can be turned in both directions, one for addition and the other for subtraction. Thus duplicate sets of tens-carry cogs are incorporated. While the Odhner machines have a closed housing, the three mechanisms of the Esser machines are separately housed. The Esser machine did not enter series production.