—, oscillations in the plane of the meridian and at right angles with the same, different, xxviii, 62.
—, simultaneous motions of the surrounding air and, S. D. Poisson, xxiii, 391.
—, E. Sabine's experiments with, and conclusions, xvii, 364.
—, on the reduction to a vacuum of the vibrations of an invariable, xvii, 365.
Penetrativeness of fluids, xix, 360.
Penguins, habits of, xlix, 151.
Pennant, Thos., life and writings of, xxxvii, 146.
Pennatule flèche, iv, 87.f
Pennine, form and analysis of, xlvii, 216.
Pennsylvania, coal beds of Wyoming, Z. Cist, iv, 1.f