4.2 Years 1900-1909

Number of slide rules: 13.

The early K&E Mannheim slide rules began to compete with their European counterparts. Inverse, folded, and cubic scales began to become available on the European slide rules. Manufacturers appear to have experimented with a variety of standard scale arrangements this decade in search of more efficient computational power. See, for example, the Dietzgen rules with their special “B” scales (1762-B), as well as the inverse scales and “triplex” scale arrangements on the Kolesch slide rules. The “log-log” scales, invented nearly a century earlier, are re-introduced by K&E on their duplex models at the end of this decade.

Some notable technical developments: Zeplin first flight; Wright Brothers and Kitty Hawk flights; Einstein’s development of special and general relativity; Ford’s Model T automobile.

Year	Maker	Model
c.1900	K&E	4041
c.1900	K&E	American
1900-1914	K&E	4054
c.1901	K&E	4041
1902-1912	Dietzgen	1765
1903	Faber	350
c.1904	Dietzgen	1762-B
c.1905	Dietzgen	1762-B
1905-1911	Kolesch	2574 Mannheim
1905-1911	Kolesch	2713 Stadia
1905-1911	Kolesch	2832 Triplex
1909	Stanley	Fuller’s Calculator Model No. 1
1909-1914	K&E	4056