During the 1950s a common piece of any rally navigator’s rally bag was the Marschalk Rally Speed Figure-Outer. This was a specially designed circular slide rule which was capable of many of the calculations required during a car rally in those days before calculators and computers.
The Marschalk Rally Speed Figure-Outer
The Marschalk Rally Speed Figure-Outer is capable of easily calculating the following rally information for the navigator:
- Time, in minutes and seconds, to travel one mile
- Indicated speedometer speed required to travel at the desired actual speed
- Corrected elapsed time for distance traveled
- Speed that is needed to make up for lost time
One of the interesting things about the Marschalk Rally Speed Figure-Outer is that the time units are in minutes and seconds. In the current format of most rallies in the United States the time units are minutes and decimal minutes taken to two or three decimal points. Canadian and European rallies use minutes and seconds.
My Marschalk Rally Speed Figure-Outer has the guidelines on how to use the device on the back of the device which is very handy because you never have to worry about where the instructions are.
Instructions on the Back of the Marschalk Rally Speed Figure-Outer
The Marschalk Rally Speed Figure-Outer was copyrighted in 1956. It appears to have been manufactured by the copyright holder, John Marschalk. The address on the back of the device indicated that Mr. Marschalk was based in Los Angeles, California.
I have been asked in the past why I have some of these older rally calculating devices such as the Curta calculator, the Stevens Rally Wheel, the Rally Cat, and this Marschalk slide rule. The main reason is to be ready for car rallies like the former Bridghampton Road Rally which had a simple navigation equipment rule which said that no electronic displays were allowed in the cars.
I don’t know if the Marschalk Rally Speed Figure-Outer was a commercial success or not. The direct competitor would have been the Stevens Rally Wheel which seems to be more common and be referred to more in today’s rally discussions and rules.
Regardless of its current usefulness, I am glad that I have one of these pieces of rallying history.