DOPPLER'S PRINCIPLE. 395 BORAN. of making the receiving instrument move away from or toward the vibrating source. This alter- ation in wave number is called 'Doppler's Trin- eiple,' having been first stated in 1S42 by Prof. Christian Dopplcr, of Prague. If the natural velocity of waves in the medium connecting the vibrating body and the receiving instrument is V, if the velocity of approach of the vibrating body is r, and if N is the natural wave-number of the waves, the new wave-number will be N', where whereas, if r is the velocity of recession of the vibrating body, If, however, the vibrating body is not moving, but the receiving instrument is receding with a velocity v, then N-=|.(Y-.); and, if v is the velocity of approach of the receiv- ing instrument, N'= ^ (V-ft,). Illustrations of Doppler's principle are af- forded in acoustics and in light. If a sounding body, e.g. a whistling locomotive, is approaching a listener, the pitch of the note heard is higher than when it is at rest or when receding. Simi- larly, if a source of light, e.g. a star or one edge of the rotating sun, is approaching an observer rapidly, the color due to any train of waves in the radiation produced in the human eye is not what would be seen if there were no relative mo- tion in the line of sight ; the color actually seen will be slightly shifted toward the blue portion of the spectrum. If a photographic plate is used to record the radiation, the actual change in wave-number can be measured, and thus an idea obtained of the velocity of the source of light. DOQXJET. See Docket. DOR, Dor-Beetle, or Dor-Bug. See Chafes; JUXE-P)UG. DORE, dOr. or iloNT Dore (often erroneously written Mont d"Or). A mountain mass in France, comprised in the great group of Aiivergne (q.v. ) ^Mountains in the Department of Puy-de- Dome (Map: France. J 6) . They are of volcanic formation, and rise in the Puy-de-Sancy, which is the highest peak of central France, to the height of 6100 feet. DO'RA. A play by Sardou. produced in 1S77, and popular in an English version imder the title of Diplomacy. DORA, Si.sTER. See Patti.son, DoROTnT WVMII.OW. DO'RAB. A fish (Chirnccntrus dorah] of the Rod Sea. Indian Ocean, and ilalayan waters, al- lied to the herrings, but having some remarkable peculiarities of structure characterizing the sepa- rate familv Chirocentridfp. "The upward direc- tion of the cleft of the mouth, which is armed with formidable teeth, coupled with the elonga- tion of the lower jaw. gives a rather peculiar ex- pression to the head, and the eyes are remarkable for being covered with skin. ... .As this fish attains a length of more than a dozen feet, it is a sufficiently formidable monster, and when Vol. VI.— 26. captured is said to bite viciously at any object within reach. Its ilesh is of poor quality." DO'RAD. A nuiiled catfish of the Amazonian genus Doras. Sec Caitish and Hassar. DORA D'ISTRIA, dn'ra de'strf-d (1828-88). A p.scudonym of Helen Ghika, Princess Koltzoff- Massalsky. She was the niece of Prince Alexan- der Gliika, Hospodar of Wallachia, and was born at Bucharest. January 22. 1S2H. Thorouglilv in- structed in the classics under the care of Profes- sor Pappadopoulos, she added to these by fre(iuent travels through Germany. France, and Italy an extensive knowledge of modern languages and lit- erature. At the age of fifteen she commenced a translation of the Iliad into German, and not long afterwards wrote several pieces for the the- atre. After her marriage with Prince Koltzofl- Massalsky she accompanied her husliand to the Court of Saint Petersburg. Her first important work. La vie nionastique dans I'cfilise nrientale, was published at Paris and Geneva in 18.55. This was followed b.v two works, Gli erol della Rumenia and / Rumeni ed il papato. Her studies in Swit- zerland resulted in a work entitled La Suisse allemande. She received an official invitation in 1865 to attend the sixtli centenary festival' in honor of the birthday of Dante. This event she described vividly in Pclerinaije au tombeau de Dante. In 1807 she went to Venice to examine the ample archives of that city; but the first thing she did was to publish ]'enise en 1SG7. -■Vtterwards she showed the fruits of her re- searches in Les Albanais musulmans and Gli .ilbanesi ncllii Rumenia; storia dei principi Ghika nei secoll XYII., Xriri., XIX. (1873). In 1SG8 she gave some account of her own active life in Di alcune opcre dclla principessa Dora d'Istria, a work which reappeared in 1871 under the title, Dora d'Istria e la poesia altmncse. Her work, Des femtnes par unc femme (1804), was transl.ated into Russian. Italian, and English. She died at Florence, Xovember 17, 1888. DORALICE, do'ra-le'cha. (1) One of the sto- ries in Straparola's Xights, and an old version of Cinderella. (2) In Ariosto's Orlando Furio.so, the daughter of the King of Granada, and w'ife, first of Mandricardo and then of Roger. (3) The fair, shrewd wife of Rhodophil in Dryden's .Uarriafie a la Mode. DO'RATT, JoH.x (1807-78). An English mis- cellaneous writer, descended from an old Irish family of Drogheda. He was born in London. He acquireil from his father, who had lived in France, a good knowledge of French. From 1823 to 1828 lie was on the Continent as tutor to a young nolilenian. He had already become a con- tributor to the Literary Chronicle. When only seventeen Ik; wrote a melodrama, which, under the title of Justice, or the Venetian Jew. was produced at the Surrey Theatre in 1824. Four years later he published a selection from his contributions to the press — Sketches and Remi- niscences ; and in 1835, Ilislory of Reading. In 1854 appeared Habits and Men, and Tabic Traits, followed by Lives of the Queens of the House of Hanover (1855); Kniphts and Their Days (1856): Mnnarchs Retired from liusiness (1857): History of Court Fools (18581: Xcn^ Pictures and Old Panels (1850) : The Princes of Wales (1860) : and a Memoir of Queen .Idelaide (1861). In 1804 he produced Their .Majesties'
