Henry Kater's triangulation survey of north Scotland. Edward Sabine's study of pendulum lengths at various latitudes. François Arago did not receive letters from JH and Francis Baily. Comments on rumor of [Isaac] Newton's madness. JH plans to reduce transit observations of fixed stars at Greenwich since [James] Bradley's time. Are French and other astronomers in agreement on common system of reductions? Will visit Paris next month. Observed curious phenomena in voltaic electricity.