Non-Decimal Calculators

Sterling Currency Calculators
Original Odhner LUSID Sterling Currency Calculator

Original Odhner LUSID

A pinwheel calculator with adaptions for use with the £sd Sterling currency.

360 x 120 x 145 mm (14.2" x 4.75" x 5.7").

This machine has serial no. 90201, so was manufactured 1929-1931[1].

At first glance, this machine looks like a fairly normal Original Odhner pinwheel machine with the standard three registers (setting levers, quotient windows, and results windows).  However, closer inspection reveals several unusual settings and markings, which are explained in the Original Odhner example calculations brochure for this model[2].  By means of the different settings the machine can be operated in the standard decimal mode or in the £sd mode.

In the accompanying photographs the machine illustrated has just performed Example 2 in the Original Odhner LUSID example calculations brochure[2].  This is a calculation to find the cost of 736.56 tons @ 11/— per ton (11 shillings per ton), giving the answer £405/2s/2d (or in decimals £405.108).

The setting levers at top right operate only in decimal notation and have been set to 736.56 (tons).
The line of quotient windows on the left (derived from the number of turns of the crank) shows 11 in the shillings columns (i.e. 11s/—).
The line of result windows in the centre shows the result of the calculation of the cost of 736.56 tons @ 11/— per ton as £405.108.  By using the sliding double shutter arrangement on the right, the machine can alternatively display the result in £sd as £405/2s/2d, as shown further down.

Below are close-up photographs showing these settings more clearly.

The line of windows of the Quotient register on the left has three sections.  At its left end are five £ windows with white numerals.  Then it has three windows with red numerals, the two left ones being for shillings and the right one for pennies.  The six white numerals on the right of this register are for decimal fractions of a penny.

The line of result windows in the centre shows the cost of 736.56 tons @ 11/— per ton in decimals as £405.108, due to the setting of the sliding double-shutter.

After sliding the knob of the double-shutter arrangement to the left the decimal fraction of the resulting £ is covered up and windows showing the equivalent as 2s/2d have been uncovered.  The result is now displayed in £sd as £405/2s/2d.

Cris Vande Velde has a page on his excellent site on mechanical calculators where he delves into the internal mechanism of the unusual LUSID calculator explaining its operation in detail and with several videos of the mechanism in action[3].

References:

1. Original Odhner serial numbers: http://www.rechenmaschinen-illustrated.com/Odhner_serialNumbers.htm
2. Original Odhner LUSID example calculations: http://www.rechenmaschinen-illustrated.com/Manuals/Odhner%20Lusid%20examples.pdf
3. Comprehensive information on the LUSID from Cris Vande Velde: http://www.crisvandevel.de/lus2.htm

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© Text & photographs copyright Nigel Tout   2000-2022  except where noted otherwise.