Rocks, their nature and configuration, 228; geognostical classification into four groups, 248-251; i. rocks of eruption, 248, 251-253; ii. sedimentary rocks, 248, 254, 255; iii. transformed, or metamorphic rocks, 248, 259, 255, 256-269; iv. conglomerates, or rocks of detritus, 269, 270; their changes from the action of heat, 258, 259; phenomena of contact, 258-269; effects of pressure and the rapidity of cooling, 258, 267.
Rose, Gustav, on the chemical elements, etc., of various aerolites, 131; on the structural relations of volcanic rocks, 254; on crystals of feldspar and albite found in granite, 251; relations of position in which granite occurs, 252-269; chemical process in the formation of various minerals, 265-269.
Ross, Sir James, his soundings with 27,000 feet of line, 160; magnetic observations at the South Pole, 187; important results of the Antarctic magnetic expedition in 1839, 192; rarity of electric explosions in high northern regions, 337.
Rossell, M. de, his magnetic oscillation experiments, and their date of publication, 186, 187.
Rothmann, confounded the setting zodiscal light with the cessation of twilight, 143.
Rozier, observation of a steady luminous appearance in the clouds, 202.
Rumker, Encke's comet, 106.
Ruppell denies the existence of active volcanoes in Kordofan, 245.
Sabine, Edward, observations on days of unusual magnetic disturbances, 178; recent magnetic observations, 184, 185, 187, 188.
Sagra, Ramon de la, observations on the mean annual quantity of rain in the
Havana, 333.