Christel (Christian) Hamann

The German engineer Christian Bernhard Julius Hamann (1870-1948) is remarkable figure in the world of mechanical calculators. He is a holder of many patents in this area and the constructor of countless mechanisms and calculators, let's mention only Gauss, Berolina, Mercedes Euklid, Hamann Manus, etc.

In 1905 The Royal Prussian Academy of Sciences in Berlin placed a considerable sum (15000 Marks, later on Imperial Academy of Sciences in Vienna granted 8000 Krones) at the disposal of German professors Julius Bauschinger (professor of Astronomy in Leipzig and director of the imperial observatory of Strassburg) and J. Peters (professor, assistant of the Royal Astrnomical Calculationg Institute of Berlin), who decided to publish tables of logarithms to eight digital places of all numbers from 1 to 200000. The work started using hand-calculations in 1908, and in the same year Bauschinger and Peters contacted Christel Hamann and requested him to put his long experience at his disposal and to construct a new machine, by means of which the values was to be reckoned from the second differences by summation and at once written down. Only several months were enough for the genius-constructor, and the machine (see the lower photo) was ready in the beginning of 1909. It immediately went into action and worked perfectly.

The difference engine of Hamann

The Tables of Bauschinger and Peters (Logarithmic-Trigonometrical Tables with eight decimal places) was published in Leipzig in 1910. A description of the machine of Hamann can be found in the preface of the book, click here to see it. (digitalized in PDF format by Stephan Weiss, www.mechrech.info, german language).