ABSTRACT
The concept of the rotor machine was developed independently by a number of inventors at a similar time. Four inventors had been credited with inventing it: Edward Hebern, Arvid Damm, Hugo Koch, and Arthur Scherbius. However, in later discovery, it was found that the first inventors of the rotor machine were two Dutch naval officers, Theo A. van Hengel and R.P.C. Spengler, in 1915 [1].
