KHE 



RHE 



press words; as a letter of attorney, a 

 submission to an award, and a testament, 

 or last will. 



By the statute of frauds, 29 Charles II. 

 C. 3. no devise of lands shall be revocable, 

 otherwise than by some other will, or codi- 

 cil, in writing-, or other writing declaring 

 the same, signed in the presence of three 

 witnesses. But still such a devise may 

 he revoked by destroying the will, or by 

 any oilier revocation by act of law ; such 

 as granting away the estate to another 

 by deed. 



REVOLUTION, in astronomy, is the 

 period of a planet or comet, &c. or its 

 course from any point of its orbit, till it 

 return to the same again. Planets have 

 a twofold revolution : one about their axis, 

 called their diurnal rotation, which consti- 

 tutes I heir day; the other, about the Sun, 

 called their annual revolution, constitut- 

 ing ^lieir year. 



REVOLUTION, in geometry, the motion 

 of rotation of aline about a fixed point 

 or centre, or of any figure about a fixed 

 axis, or upon any line or surface. THUS 

 the revolution of a given line about a fixed 

 centre, generates a circle ; and that of a 

 right-angled triangle about one side, as 

 an axis, generates a cone ; and that of a 

 semicircle about its diameter generates a 

 sphere or globe. 



RHABDOLOGY, in arithmetic, the 

 doctrine of Neper's rods. Ste NEPER. 

 RHAMNUS, in botany, bnck-thom, a 

 genus of the Pentandria Monogynia class 

 and order. Natural order of Dumosjc. 

 lihamni, Jussieu. Essential character: ca- 

 lyx tubular: corolla scales defending the 

 stamens inserted into the calyx; berry. 

 There are forty-two species. 



RHAPIS, in botany, a genus of the 

 Appendix Palma;. Natural order of Palms. 

 Essential character : caiyx trifid ; corolla 

 trifid ; stamens six ; pistil one. There are 

 two species, viz. R. fiabelliformis, creep- 

 ing rooted rhapis, or ground rotan ; and 

 R. arundinacea, simple-leaved rliapis, 



RHEEDIA, in botany, so named in me- 

 mory of Henry Kheede Van Draakenstein, 

 a genus of the Polyanrlria Monogynia 

 class and order. Natural order of Gut- 

 tiferse, Jussieu. Essential character : caiyx 

 none ; corolla four-petalu d ; berry three- 

 sided. There is but one species, viz. R. 

 lateridora. 



RHETICUS (GKORKB JOACHIM), in bi- 

 ography, a noted Gorman astronomer 

 and mathematician, was born at Feldkirk, 

 in Tyrol, the 15th of February, 1514. 

 After imbibing the elements of'the ma- 

 thematics at Tig-uri, with Oawuld Mycone, 



lie went to Wittemberg, where he dili- 

 gently cultivated that science. Here he 

 was made master of Philosophy in 1535, 

 and professor in 1537. He quitted this 

 situation, however, two years after, and 

 went to Fruenbergto put himself under 

 the assistance of the celebrated Coperni- 

 cus, being induced to this step by his 

 zeal for astronomical pursuits, and the 

 great fame which Copernicus had then 

 acquired. Rheticus assisted this astrono- 

 mer for some years, and constantly ex- 

 horted him to perfect his work, De Revo- 

 lutionibus, which he published after the 

 death of Copernicus, viz. in 1543, folio, 

 at Norimberg, together with an illustra- 

 tion of the same in a narration, dedicated 

 to Schoner. Here too, to render astro- 

 nomical calculations more accurate, he 

 began his very elaborate canon of sines, 

 tangents, and secants, to fifteen places of 

 figures, and to every ten seconds of the 

 quadrant, a design which he did not live 

 quite to complete. The canon of sines, 

 however, to that radius, for every ten se- 

 conds, ami for every single second in the 

 first and last de-.gree of the quadrant, com- 

 puted by him, was published in folio, at 

 Fr'anckfort, 1613, by Pitiscus, who him- 

 self added a few of the first ni.;es comput- 

 ed to twenty-two places of figures, liut 

 the larger \vork or ca/uui of twines, tan- 

 gents, and secants, to eve^y ten second?, 

 was perfected and published :t f 

 death, viz. in 1596, by ;i ; s disciple, "Val- 

 entine Otho, mathematician to the Elec- 

 toral Prince Palatine. 



After the death of Copernicus, Rheti- 

 cus returned to Wittenberg-, viz. in iJ41 

 or 1542, and was again admitted, to his of- 

 fice of professor of math ens. > <:<. 'i : :;> 

 same year, by the recommen ra 

 Melancthon, he went to Noii' 

 where he found certain man use i . 

 Werner and Regiomontanus. He after- 

 wards taught mathematics at Leipsic. 

 From Saxony he departed a second 

 time, for what reason is not known, and 

 went to Poland ; and from thence to 

 Cassovia, in Hungary, where he died 

 December the 4th, 1576, near sixty- 

 three years of age. 



His Narratio de Libris Revolutiomim 

 Copernici, was first published at Gedu- 

 num, in quarto, 1540, and afterwards 

 added to the additions of Copernicus's 

 work. He also composed and publish- 

 ed Ephemerides, according to the doc- 

 trine of Copernicus, till the year 1551. 

 Rheticus also projected other works, 

 and partly execute i them, though they 

 were never published, of various kinds, 



