ROGATION DAYS 91 ROGERS that these newly discovered rays gen- erated in the neighborhood of the Crookes tube by the electric disturbance set up by the passage of a current possessed the property of passing through all bodies in their path, and that some bodies, being less permeable than others, cast a shadow. Subsequent experiments have established the fact that the transparency of a body to the X-rays is proportional to its den- sity. As to the real nature of the X-rays eminent physicists differ, but all agree that they must be regarded as of a na- ture essentially different from ordinary light. They cast an invisible life-size shadow of the objects that obstruct their passage, which invisible shadow if re- ceived on a surface which phosphoresces or glows under their action becomes a visible shadow, which makes the wonder- ful revelations of the fluoroscope possible. If this invisible shadow is received on a sensitive plate, the plate is impressed, and on subsequent development the represen- tation of the obstructing object is per- petuated on the photographic plate. The Roentgen rays pass very freely through the various tissues and fluids of the body, but are obstructed by the bones; hence it is possible to take a per- fect shadow-picture, or radiograph, as it is now generally called, of the bones of a living person or animal. By far the most important result of the discovery has been the application of the new rays to surgery. Needles, bullets and other foreign objects in various parts of the body have been successfully located, and the invention of the Fluoroscope (q. v.) has made it possible to use the Roentgen rays, not only in surgical cases, in search- ing for fractures, etc., but to undertake anatomical studies and make the diag- nosis of internal diseases. The full physiological effects of the X-rays are not yet clearly understood. Experiments show that long exposure to the rays causes acute maladies of the skin and also baldness. ROGATION DAYS, the Monday, Tues- day, and Wednesday before Holy Thurs- day or Ascension Day, so called from the supplications or litanies which are ap- pointed in the Roman Catholic Church to be sung or recited in public procession by the clergy and people. In England, after the Reformation, this practice was discontinued, but it survives in the cus- tom (observed in some places) of per- ambulating the parish boundaries. ROGER I., Count of Sicily, the young- est of the 12 sons of Tancred de Haute- yille of Normandy; born in that duchy in 1031. When 27 years of age he joined his famous brother Robert Guiscard in south Italy; but at first he seems to have fought against Robert more than he helped him. At length they became re- conciled, and Roger helped Robert to com- plete the conquest of Calabria. In 1060 Roger was invited to Sicily to fight against the Saracens: he took Messina and settled a garrison there. Every- where the Normans were welcomed by the Christians of Sicily as their deliverers from the Moslem yoke, and they won town after town, till in 1072 the Saracen capital, Palermo, was captured. Robert then invested Roger with the countship of Sicily. Count Roger spent the rest of his life, apart from his numerous expe- ditions undertaken for the support of his brother, in completing the conquest of Sicily, which was finally effected in 1090. Already as early as 1060 Duke Robert had given his brother the half of Cala- bria, with the title of count. After Robert's death (1085) Roger succeeded to his Italian possessions, and became the head of the Norman power in southern Europe. Pope Urban II. granted him special ecclesiastical privileges, such as the power to appoint the bishops, and made him papal legate of Sicily (1098). Roger died in Mileto, Calabria, in June, 1101. ROGER II., King of Sicily, second son of the preceding; born in 1093. When he came of age he executed his task of governing Sicily with great ability and courage, and his sway was gradually ex- tended over a great part of southern Italy. By the Anti-Pope Anacletus in 1130 he was honored with the title of king. In spite of repeated revolts of the barons, and though the German Emperor Lothair and the Greek Emperor Em- manuel were leagued against him, and Innocent II. excommunicated him, he de- fended himself with success and defeated the Pope's forces at Galluzzo, taking Innocent prisoner. Peace was made, the Pope annulled all excommunication against Roger, and recognized his title of king. Roger afterward fought with success against the Greeks, took Corfu, and gained part of the N. coast of Africa. He died in 1154, and was succeeded by a son and a grandson. ROGERS, HENRY HTJDDLESTONE, an American capitalist, born at Fair- haven, Mass., in 1840. He was educated in the Fairhaven High School, and after being newspaper seller, clerk, and rail- road worker, went to Pennsylvania and settled at McClintock's Wells. Here he entered the oil business and had great success in the kerosene industry. In 1870 he settled in New York and in 1874 co- operated in the establishment of the
