Thomas Robert Malthus. An Essay on the Principle of Population, edited by Patricia James, 2 vols. Cambridge: Cambridge University Press for the Royal Economic Society, 1990. Pp. xvi + 446; vi + 397. ISBN 0-521-32361-4. L.75, $120.00.Thomas Robert Malthus. Principles of Political Economy, variorum edition, edited by John Pullen, 2 vols. Cambridge: Cambridge University Press for the Royal Economic Society, 1989. Pp. lxix + vi + 601; 507. ISBN 0-521-24775-6. L. 75.00, $120.00.