sidereal clock

A clock regulated to measure sidereal time, reckoned by sidereal days of 23 h. 56 m. 4s. mean solar time, which are measured by the interval between two succe ive pa ages of any fixed star over the same meridian, and divided into twenty-four sidereal hours. sidereal-day, s. [DAY (1), s.,.] sidereal-magnetism, s. IMG:content-1437.png:[blocks in formation] Carbonic acid, 37.9; protoxide of iron, 62'1=100, which is equivalent to the formula, FeO, CO2, but part of the iron is frequently replaced by manganese, magnesium, or calcium, giving rise to numerous varieties, which Dana divides as follows: fate, făt, färe, amidst, what, fall, father; we, wet, here, camel, her, there; A. Ordinary: (1) Crystallized; (2) concretionary (sphærosiderite); (3) granular to compact ma ive; (4) oõlitic; (5) earthy. B. By replacing part of the iron: (1) Nearly pure; (2) containing five to twelve per cent. of protoxide of manganese, with a little magnesia and lime; (3) containing seventeen to eighteen per cent. of protoxide of manganese, having the formula, 24 FeOCO2+ MnOCO2; (4) containing twenty-five per cent. of protoxide of manganese, the oligonite, with formula, 14 FeOCO2+MnOCO2; (5) containing little manganese and much magnesia, with the formula, 4FeOCO2+MgOCO2; (6) a similar composition, with specific gravity 3'616-3-660, the sideroplesite; (7) containing twenty per cent. of carbonate of lime with formula, 8FeOCO2+2MnOCO2+3CaOCO2; and (8) including all other kinds. A widely distributed mineral, but only occasionally found in sufficient abundance to work as an iron ore, except as the principal constituent of clay-ironstones. 2. The name given to those meteorites which consist wholly of iron. 3. The same as SAPPHIRE-QUARTZ (q. v.). 4. The same as LAZULITE (q. v.).