(1782–1865), was also a politician of some note in his day.
Among P. L. Roederer's writings may be mentioned Louis XII. (1820); François I. (1825); Comédies historiques (1827–30); L'Esprit de la révolution de 1789 (1831); La Première et la deuxième année du consulat de Bonaparte (1802); Chronique des cinquante jours, an account of the events of the 10th of August 1792; and Mémoire pour servir a l'histoire de la société polie en France (1835).
See his Œuvres, edited by his son (Paris, 1853 seq.); Sainte-Beuve, Causeries du lundi, vol. viii.; M. Mignet, Notices historiques (Paris, 1853).
ROEMER, FRIEDRICH ADOLPH (1809–1869), German geologist, was born at Hildesheim, in Prussia, on the 14th of
April 1809. His father was a lawyer and councillor of the
high court of justice. In 1845 he became professor, of
mineralogy and geology at Clausthal, and in 1862 director
of the School of Mines. He first described the Cretaceous and
Jurassic strata of Germany in elaborate works entitled Die
Versteinerungen des Norddeutschen Oolithen-gebirges (1836–39),
Die Versteinerungen des Norddeutschen Kreidegebirges (1840–1841)
and Die Versteinerungen des Harzgebirges (1843). He
died at Clausthal on the 25th of November 1869.
His brother, Carl Ferdinand von Roemer (1818–1891), who had been educated for the legal profession at Göttingen, also became interested in geology, and abandoning law in 1840, studied science at the university of Berlin, where he graduated Ph.D. in 1842. Two years later he published his first work, Das Rheinische Übergangsgebirge (1844), in which he dealt with the older rocks and fossils. In 1845 he paid a visit to America, and devoted a year and a half to a careful study of the geology of Texas and other Southern states. He published at Bonn in 1849 a general work entitled Texas, while the results of his investigations of the Cretaceous rocks and fossils were published three years later in a treatise, Die Kreidebildungen von Texas und ihre organischen Einschlüsse (1852), which included also a general account of the geology, and gained for him the title “Father of the geology of Texas.” Subsequently he published at Breslau Die Silurische Fauna des westlichen Tennessee (1860). During the preparation of these works he was from 1847 to 1855 “privat-docent” at Bonn, and was then appointed professor of geology, palaeontology and mineralogy in the university of Breslau, a post which he held with signal success as a teacher until his death. As a palaeontologist he made important contributions to our knowledge especially of the invertebrata of the Devonian and older rocks. He assisted H. G. Bronn with the third edition of the Lethaea geognastica (1851–56), and subsequently he laboured on an enlarged and revised edition, of which he published one section, Lethaea palaeozoica (1876–1883). In 1862 he was called on to superintend the preparation of a geological map of Upper Silesia, and the results of his researches were embodied in his Geologie von Oberschlesien (3 vols., 1870). As a mineralogist he was likewise well known, more particularly by his practical teachings and by the collection he formed in the Museum at Breslau. He died at Breslau on the 14th of December 1891.
ROEMER, OLE (Latinized Olaus) (1644–1710), Danish astronomer,
was born at Aarhuus in Jutland on the 25th of September
1644. He became in 1662 the pupil and amanuensis of Erasmus
Bartholinus at Copenhagen, and assisted J. Picard in 1671 to
determine the geographical position of Tycho Brahe’s observatory
(Uraniborg on the island of Hveen). In 1672 he accompanied
Picard to Paris, where he remained nine years, occupied.
with observations at the new royal observatory and hydraulic
works at Versailles and Marly. On the 22nd of November
1675 he read a paper before the Academy on the successive
propagation of light as revealed by a certain inequality in the
motion of the first of Jupiter’s satellites. A scientific mission
to England in 1679 made him acquainted with Newton, Halley
and Flamsteed. In 1681, on the summons of Christian V.,
king of Denmark, he returned to Copenhagen as royal mathematician
and professor of astronomy in the university; and
from 1688 he discharged, besides, many important administrative functions, including those of mayor (1705), chief of
police and privy councillor. He died at Copenhagen on the
23rd of September 1710
Roemer will always be remembered as the discoverer of the
finite velocity of light. He showed besides wonderful ingenuity
in the improvement of astronomical apparatus. The
first transit instrument worthy the name was in 1690 erected
in his house. In the same year he set up in the university
observatory an instrument with altitude and azimuth circles
(for observing equal altitudes on both sides of the meridian)
and an equatorial telescope. In 1704 he built, at his own cost,
the so-called “Tusculan” observatory at Vridlösemagle, a
few miles west of Copenhagen, and equipped it with a meridian
circle (the transit instrument and vertical circle combined) and
a transit moving in the prime vertical. Roemer-thus effectively
realized nearly all our modern instruments of precision, and
accumulated with them a large mass of observations, all of
which unfortunately perished in the great conflagration of the
21st of October 1728, except the three nights’ work discussed
by J. G. Galle (O. Roemeri triduum observations astronomic arum
a. 1706 institutarum, Berlin, 1845).
See E. Philipsen, Nordisk Universitets Tidskrift, v. 11 (1860); P. Horrebow, Basis Astronomiae (Copenhagen, 1735); J. B. J. Delambre, Hist. de l’astr. moderne, ii. 632; J. F. Montucla, Hist. des mathématiques, ii. 487, 579; R. Grant, Hist. of Phys. Astronomy, p. 461; R. Wolf, Gesch. der Astronomie, pp. 452, 489, 576; J. F. Weidler, Historia Astronomie, p. 538; W. Doberck, Nature, xvii. 105; C. Huygens, (Œuvres complètes, t. viii. pp. 30–58; L. Ambronn, Handbuch der astr. Instrumentenkunde, ii. 552, 966; T. J. J. See, Pop. Astronomy, No. 105, May 1903.
ROERMOND, a town in the province of Limburg, Holland,
on the right bank of the Maas at the confluence of the Roer,
and a junction station 28 m. by rail N.N.E. of Maastricht.
Pop. (1900) 12,348. The old fortifications have been dismantled
and partly converted into fine promenades. At this
point the Maas is crossed by a bridge erected in 1866–67, and
the Roer by one dating from 1771, replacing an older structure,
and connecting Roermond with the suburb of St Jacob.
Roermond is the seat of a Roman Catholic episcopal see. The
finest building in the town is the Romanesque minster church
of the first quarter of the 13th century. In the middle of the
nave is the tomb of Gerhard III., count of Gelderland, and his
wife Margaret of Brabant. It was formerly the church of a
Cistercian nunnery, and in modern times has been elaborately
restored. The cathedral of St Christopher is also of note; on
the top of the tower (246 ft.) is a copper. statue of the saint, and
the interior is adorned with paintings by Rubens, Jacob de
Wit (1695–1754) and others. The Reformed church was once
the chapel of the monastery of the Minorites. There is also
a Redemptorist chapel. The old bishop's palace is now the
courthouse, and the old Jesuits' monastery with its fine gardens
a higher-burgher school. Woollen, cotton, silk and mixed
stuffs, paper, flour and beer are manufactured at Roermond.
Close to Roermond on the west is the village of Horn, once
the seat of a lordship of the same name, which is first mentioned
in a document of 1166. The lordship of Horn was a fief of
the counts of Loon, and after 1361 of the bishop of Liége; but
in 1450 it was raised to a countship by the Emperor Frederick II.
On the extinction of the house of Horn in 1540, the countship
passed to the famous Philip of Montmorency, who, with the
count of Egmont, was executed in Brussels in 1568 by order of
the duke of Alva. In the beginning of the next century the
count ship was forcibly retained by the see of Liége, and was
incorporated in the French department of the Lower Maas at
the end of the 18th century. The ancient castle is in an excellent
state of preservation and is sometimes used for the
assembly of the states.
ROGATION DAYS (Lat. rogatio, from rogare, to beseech; the equivalent of Gr. λιτανεία, litany), in the Calendar of the Christian Church, the Monday, Tuesday and Wednesday before Ascension Day, so called because long associated with the chanting of litanies in procession (rogationes). The week in which they occur is sometimes called Rogation Week. In 511
