Karl Eduard Senff (20 April 1810 Tartu – 12 January 1849 Tartu) Acting director 1839-1840

Senff was born as a son of the teacher of drawing and engraving of Tartu University. Having graduated from the local high school, he began to study mathematics at Tartu University and graduated from it in 1830 with a degree of a candidate. Being a student, he already worked as an assistant in the observatory. His competition paper Theoremata principalia e theoria curvarum et superficierum was awarded with the golden medal by the Council of Tartu University and in 1831 it was published. It is the first systematic treatment of the theory of the lines and surfaces where he derived the equations similar to those of Frenet but 17 years before J. Frenet. The years of further education in Germany followed. He stayed longer in Königsberg where he defended his Doctoral thesis. To obtain the right for lecturing as a private assistant professor, Senff had to present Tartu University an astronomical paper De distantiis, quae inter stellam et lunae marginem, vel inter margines solis et lunae observatae sunt, propter formam horum astrorum refractione mutatam corrigendis. In connection with the death of the professor of mathematics Martin Bartels in 1836 Senff had to start delivering lectures in all mathematical disciplines. In the following year he was appointed professor extraordinary of pure and applied mathematics and the head of the mathematics centre of Tartu University.

In 1838 Senff defended in Tartu his Doctoral thesis Elementa calculi variationum ejusque usus in solvendis problematibus analyticis et geometricis and in 1839 he was appointed professor ordinary.

When Struve left for Pulkovo in the spring of 1839, Senff was appointed the temporary director of the Observatory of Tartu. The Council of the University, on recommendation of Struve, had elected Peter Andreas Hansen (1795-1874) the new director but Hansen refused to take the post. In March 1840 at the new council elections the new astronomer Johann Heinrich Mädler from Berlin was preferred. In the academic year 1842/43 a separate chair for applied mathematics was established at Tartu University, Ernst Ferdinand Adolf Minding (1806-1885) becoming its professor. Senff gave him the responsibilities of leading the mathematics centre in 1843.