Calculators have a long and noble history, starting out as human beings, then becoming mechanical things of gears and cranks, then assemblages of relays, valves, transistors... and finally little palm-held miracles of electronics.

The wristwatch, meanwhile, has likewise evolved from a mechanical timepiece, via electromechanical hybrids, and onward to the digital watch, and thence the smartwatch.

Somewhere along the line, these two evolutionary lines merged to produce the calculator watch - a chunky digital timepiece with an array of tiny buttons for performing off- the-cuff electronic calculations.

But wait! Surely, an evolutionary step has been missed! Where is the mechanical wrist calculator?

Proposed, therefore, is such a machine. Crafted by a certifiably insane watchmaker, it will be the wrist-borne, miniaturized mechanical equivalent of the Marchant hand- cranked calculator. Driven by a tiny crank which folds out from the side of the watch, it will perform mechanical mathematics by means of an exquisitely miniaturized set of gears and cams, displaying the answer in a barely- readable odometer-style display set into the face.
-- MaxwellBuchanan, Feb 01 2016

Curta https://en.wikipedia.org/wiki/Curta
almost... [piluso, Feb 01 2016]

I love it. And for the other wrist a mechanical typewriter, please.
-- Toto Anders, Feb 01 2016


Arabic or Roman numerals ? Only a limited number of certifiably insane watchmakers are available, don't want to waste their time.

MB((where the Etruscans were displaced by Gauls) once again the French seem to have invented it. )
-- popbottle, Feb 01 2016


The problem with Roman numerals is that they're complete bollocks. So we'll be going with Arabic numerals, which are Indian, rather than Roman numerals, which are Etruscan.
-- MaxwellBuchanan, Feb 01 2016


[+] but the folding crank sounds a bit fragile. I suggest gearing it to the bezel ring instead.
-- scad mientist, Feb 01 2016


[scad mientist] - I was thinking the exact same thing!
-- neutrinos_shadow, Feb 01 2016


I wish I were smart enough to recommend a bezel ring.
-- Voice, Feb 02 2016


[+]

//Driven by a tiny crank// which winds the watch spring which operates the multiplexed comptometer.
-- FlyingToaster, Feb 02 2016


Nice - will it print out answers onto a roll of very thin paper?
-- hippo, Feb 02 2016


A printer would be a distinct improvement. Perhaps a tiny Linotype machine?
-- MaxwellBuchanan, Feb 02 2016


Don't make it to complicated in the first step. Just read the (mechanical) display and type the numbers with my miniature typewriter on the other wrist.
-- Toto Anders, Feb 02 2016


I'm pretty sure that a system of cables and pulleys, running up one sleeve and down the other, could be used to connect the mechanical calculator watch to your wrist typewriter.
-- MaxwellBuchanan, Feb 02 2016


[+] A self-winding mechanism would be a proper power source for this device.
-- piluso, Feb 02 2016


//A self-winding mechanism//

I don't think we should piss about with a simple, one-rotor self-winder. Such rotors capture energy efficiently only at certain speeds of arm movement. What we need is a nested series of concentric rotors, each working best under different conditions. A fairly simple gearing system should then be able to extract the available energy from whichever rotor(s) is/are delivering the most at any given time.

Actually I may post that as an independent half- idea.
-- MaxwellBuchanan, Feb 02 2016


I did actually think of this myself quite some time ago but didn't post it. Never mind, it's clearly a good idea [+].
-- nineteenthly, Feb 07 2016


//Driven by a tiny crank//

Is that a slightly obscure reference to Donald Trump ?
-- 8th of 7, Feb 07 2016


Actually, an even smallerer step would use a rotary slide rule logarithmic scale whatnot.
-- Ling, Feb 08 2016


Rotary slide rule watches exist.
-- MaxwellBuchanan, Feb 08 2016



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