Perry, J., and W. E. Ayrton. On a Neglected Principle that may be Employed in Earthquake Measurement.

— See Trans. Seis. Soc. of Japan.

Philosophical Magazine.

Pickering, Rev. R. An Address to those who have either retired or intend to leave Town under the Imaginary Apprehension of the Approaching Shock of another Earthquake. 1750.

Ray, J., F.R.S. A Summary of the Causes of the Alterations which have happened to the Face of the Earth.

Rockstroh, E. Informe de la Comision Científica del Instituto Nacional de Guatemala, nombrada por el Sr. Ministro de Instruccion Pública para el Estudio de los Fenómenos Volcánicos en el Lago de Ilopango. 1880.

Rockwood, Prof. C. G. Notes on Earthquakes. Annually in the Am. Jour. Sci.

— Japanese Seismology. Am. Jour. Sci., XXII. Dec. 1881.

Romaine, W. A Discourse occasioned by the Late Earthquake. 1755.

Rossi, Prof. M. S. di. Intorno all’ odierna fase dei Terremoti in Italia, e segnatamente sul Terremoto in Casamicciola del 4 Marzo 1881. Società Geografica Italiana. 1881.