If certain objects work well, no one notices them. As with "black boxes, " their success may be gauged by their relative invisibility -- and this was the indirect goal of the objects that Julian Yates considers here: the portrait miniature, the relic, the privy (flush toilet), the printed text, and the priest-hole (a secret hiding place for Catholic priests in Protestant England).Because each of these contrivances was prone to error, misuse, and sometimes...