Richard Jensen (fl. 1902-1917) Berlin.

Jensen's first listing in the Berlin Adressbuch 1902.           

Reisszeugfabrik Richard Jensen first appears in the Berlin directory in 1902, and the listing indicates that he sells wholesale and exports. How large the factory is and how many workers employed is unknown. The factory's address is then listed at Dennewitzstraße 32. Several patents by Jensen are known. DRGM 217485 from 1904 seems to be Jensen's first drawing instrument patent and is described in length in Pädagogischer Jahresbericht in 1905 [1]. His other patent DRP 233102 is for a folding beam compass. 

Reisszeugfabrik Richard Jensen probably went out of business before the close of WW1 - it is last listed in the Berlin directory of 1917. 

1902-1905: W57 Dennewitzstraße 32

1906-1913: W35 Karlsbad 15

1914-1917: W57 Bülowstraße 56

This drawing set has compasses based on Jensen's patent DRGM 286358 from 1906, and are stamped Jensen, and the joint can be manually fastened or loosened by twisting the top [4]. The pen and pencil inserts as well as the lengthening bar are of a simple press fit construction, and they are held in their sockets without the use of a thumbscrew.

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[1] Patent DRGM 217485. Pädagogischer Jahresbericht p.536, 1905, Internet Archive

[2] DRGM 217485. Der Mechaniker p.60, 1904, Internet Archive.

[3] DRGM 233102. Der Mechanilker p.228, 1904. Internet Archive.

[4] Jensen's clamping devise was preceded by a similar devise 'Wild's Zirkelkopf-Spanngriff' by Wild & Cie (Suhr-Aarau) patent CH16587A (1899).