Abstract
This article describes items in the Science Museum, London, that have been invented for the purpose of avoiding mental calculation. As far as possible they are assessed as to whether or not they could be regarded as successful. They are also discussed in the context of the perennial debate as to whether avoiding arithmetic is desirable or not. The article is based on a talk given to a BSHM meeting on the Mechanisation of Mathematics, held at Rewley House, Oxford, in 2008.
Acknowledgement
I thank Mike Williams and Stephen Johnston for their assistance with information for this article.