JACOB'S LADDER 225 JADE with Louis N. Parker a play entitled "Beauty and the Barge." JACOB'S LADDER (Polemonium coeruleam) , a herbaceous perennial plant of the natural order Polemoniaceie, a doubtful native of Great Britain, but more common in Central and Southern Europe, and found also in the temperate parts of Asia and of North America. It is common in flower gardens in Great Britain. It has pinnate leaves, with ovato-lanceolate leaflets, a smooth stem 1 '2 to 2 feet high, and a terminal pan- icle of bright blue (sometimes white) flowers, with wheel-shaped five-lobed corolla. Great medicinal virtues were once ascribed to it, but the only quality which it seems to possess is a slight astringency. JACOB'S STAFF, a pilgrim's staff, so designated from the pilgrimages made to the Shrine of St. James at Compostella in Spain. Also a staff containing a con- cealed dagger. In surveying, an instrument for tak- ing altitudes, having a brass circle divided into four equal parts by two diametric lines. At each extremity is a perpendicular riglet over the lines, with a hole below each slit for discovering objects. The cross is mounted on a staff. Also an instrument used to measure dis- tances and heights. Also a straight rod shod with iron, and with a socket joint and pintle at the summit for supporting a surveyor's circumferentor. JACOB'S STONE, a stone fabulously said to be that on which Jacob rested his head at Luz, which was used as the coronation stone of the kings of Scot- land at Scone, in Perthshire, and was thence transferred by Edward I. to West- minster, where it still remains, inclosed in the coronation chair. JACOBUS, MELANCTHON WIL- LLA.MS, an American educator, born in Allegheny City, Pa., in 1855. He gradu- ated from Princeton University in 1877, and from Princeton Theological Semi- nary in 1881. Following study abroad, he was ordained to the Presbyterian min- istry in 1884. After serving on the faculty of the Hartford Theological Seminary he was appointed acting presi- dent of that institution in 1902, and be- came dean of the faculty in 1903. He was acting pastor of the Central Con- gregational Church of Hartford from 1889 to 1900. He was director of theology in several colleges and universi- ties. He wrote several works on theolog- ical subjects, including "A Problem in New Testament Criticism" (1900); "Commentary on the Gospel of Mark." He contributed theological articles to sev- eral encyclopedias. JACOBY, HAROLD, an American as- tronomer, born in New York City in 1865. He graduated from Columbia University in 1885 and took post-gradu- ate courses at that university. He oc- cupied several places in the astronomical department of Columbia University and became professor of astronomy in 1904. He was acting director of the observa- tory at Columbia from 1903 to 1906, and in the latter year became director. In 1889 and 1890 he was assistant as- tronomer for the United States eclipse expedition to West Africa. He was a member of many astronomical and scien- tific societies. He wrote much on as- tronomical subjects and his chief works are "Practical Talks by an Astronomer" (1903); "Navigation" (1917). He also contributed many articles to newspapers and magazines and to several encyclo- pedias. JACQUARD LOOM, a loom for weav- ing figured goods. JACQUERIE (zhak-er-e'), a name popularly given to a revolt of the French peasantry against the nobility, which took place while King John was a pris- oner in England in 1358. Jacques Bcn- homme was a term of derision applied by the nobles to the peasants, from which the insurrection took its name. It be- gan in the Beauvais, under a chief of the name of Caillet, and desolated Pi- cardy, Artois, and Brie, where savage reprisals were executed against the no- bility for their oppressions. It was sup- pressed after some weeks. JACUHY (zha-ko-e'), a river of Brazil, province of Sao Pedro do Rio Grande; length, about 250 miles. JACUSI (jak-o'se), in Japanese my- thology, the god of medicine. JADE, a name applied to about 150 varieties of ornamental stones, but should be properly restricted to the min- eral nephrite, so called from the Greek nephros because it was supposed by the ancients to have virtue in renal diseases. The name is from the Spanish ijada, "the flank" (from the Latin ilia), because it was believed to cure pain in the side; and the mineral was brought by the Span- iards from Mexico. True jade is a na- tive silicate of calcium and magnesium, tough, and of various shades of green, yellowish-gray, and greenish-white. It is principally found in China, Siberia, New Zealand, and in some of the islands of the South Pacific, while its occurrence
