page 271 note * The mention of the use of mathematics in alleviating the tedium of banishment may well recall the investigations on projective methods carried on by Poncelet in his Russian prison. Perhaps the following instance is less known: “Newton (i.e. John Newton, afterwards the friend of Cowper) became the overseer of one of those depôts of slaves maintained at the mouths of the great African rivers. . . . But he sank into a bondage only less deplorable than that of his unhappy captives. ... As he traversed the shore from one pestilential estuary to another, the unhappy outcast would have been as destitute of solace from within as from without had it not happened that a copy of Barrow’s Euclid had stuck by him in all his wanderings, and as he traced the diagrams on the sand and revolved the demonstrations his sorrows took a temporary flight.”— Essays by Sir J. Stephen, 1850.