ABSTRACT
The book begins and ends with two men in prison, one in the Tower, the other in Ely, at exactly the same time, each writing in an encrypted language. In his prison in Ely, Sir Thomas Tresham was developing a complex language of mathematical and theological symbols, so that his drawings would not be wiped away. In the Tower, in the same summer of 1597, Father John Gerard, S.J., was making rosaries out of orange peel, and storing the orange juice to write, with an adapted tooth pick, on the paper ostensibly wrapping the peel-rosaries, which he was sending first to his fellow-prisoners and then to friends outside:
In the pencilled letter I confined myself to spiritual topics, but in the white spaces between the lines I gave detailed instructions to different friends of mine outside . . . Orange juice is different. It cannot be read with water - water, in fact, washes away the writing and nothing can recover it. Heat brings it out, but it stays out. So a letter in orange juice cannot be delivered without the recipient knowing whether or not it has been read.1
