4.5 Years 1930-1939

Number of slide rules: 36.

The vector slide rules became readily available, and a modified Rietz system for the needs of engineers – the System Darmstadt – was established in Germany in 1934. The Darmstadt arrangement placed log-log scales on the back of the slide, and typically includes a P scale on the front. An expansion of Specialty Slide Rules began to take place.

Some notable technical developments: radio, discovery of neutron, nuclear fission, cyclotron patented; radar.

Year	Maker	Model
c.1930	Hemmi	40
1930	K&E	4093-3
c.1930	MARC	promo
c.1930	MARC	promo
c.1930	Nestler	24
1930-1935	K&E	4058W
c.1931	Gilson	Atlas
1931-1934	Hemmi	153
1933	K&E	4092-3
1933	K&E	4093-3
1934	K&E	4095-3
1934	K&E	Mystery
1935	Faber-Castell	387
c.1935	Hemmi	50/1
c.1935	Hemmi	80/3
1935	K&E	N4096
c.1935	Novotni	Weight Calculator
1935-1938	Lawrence	8-B
1935-1938	Lawrence	10-C
1936	K&E	Mystery2
1936	K&E	N4092-5
1936-1940	Hemmi	153
1936-1943	K&E	4058W
1936-43	Hemmi	32
1937	K&E	N4053-5
1937	K&E	4081-3
1937-1945	Nestler	23R
1938	Festus	10
1938	Festus	Acu-Rule 10D
1938	Festus	50
c.1938	Hemmi	153
1938	K&E	N4100
1939	Acu-Rule	50
1939	K&E	N4053-3
1939	K&E	4080-3
1939-1947	UIF Shanghai	4083-3