Unfortunately this is all too common a story. In our electronic age, mechanical computers seem destined to be mere quaint footnotes to history. In reality, their significance was considerable. Notably, the Turing ‘Bombe’, crucial to Britain's decoding of German Enigma messages in World War II, was a programmable mechanical computer, albeit not “absolutely general” machine like the Analytical Engine.
Recent developments, however, may yet revive mechanical calculation in mainstream science. At the web site of Sandia National Laboratories, USA (http://www.mdl.sandia.gov/micromachine/) Babbage recently learned of some delightful ‘micromachines’ no larger than a pollen grain. Formed as an integral part of a CMOS microchip, these devices include locks, shutters, sensors, encoders, and even a steam engine.
Moving down to atomic scales takes us into the realm of Dr K Eric Drexler’s ‘nanotechnology’. Atomic-scale gears and bearings are theoretically possible, and from these, nanocomputers could be built. Babbage finds most amusing the thought of a nano-sized Analytical Engine driven by a steam motor little larger. A more likely component, however, is the sliding ‘molecular abacus’ reported in the February/March 1999 issue of Scientific Computing World. It seems that Mr Fowler’s sliding-rod concept, albeit on a far different scale from his prototype, could at last find application.
A footnote from Babbage: I was delighted to read in the Western Morning News, August 30th 2000, an item about two reconstructions of Mr Fowler's Engine by Roy Foster, an engineer from Torrington, and Mark Glusker, a product designer from California. The construction was made possible through the work of historian Pamela Vass, also of Torrington, whose research led to the rediscovery of Fowler's notes on his Engine's design, given as a deathbed dictation to his daughter. A short biography of Fowler may be found at www.thomasfowler.org.uk; Mark Glusker's model may be seen at www.mortati.com/glusker/.