designed so as to throw down or 

 throw back the flame or the -hot 

 gases employed upon the material 

 on the furnace hearth, that is to 

 say, to make them reverberate from 

 the arch or crown. Various forms 

 are in use, but they are mostly 

 rectangular in plan and consist 

 essentially of two parts, the 

 hearth or bed upon which the 

 material to be treated is deposited, 

 and the fire place or grate where 

 the fuel is burned. 



These two parts may be close 

 together in the one structure, or 

 they may be separated by a con- 

 siderable distance. The grate may 

 be dispensed with and the fuel 

 brought to the furnace in the form 

 of gas from a producer in a separate 

 establishment altogether ; and 

 ignited only as it enters the rever- 

 beratory furnace. In any case 

 it will be seen that this type of fur- 

 nace is distinguished from the blast 

 furnace and some other kinds 

 by the fact that the fuel need not 

 be, and generally is not, in contact 

 or mixed with the ore on the 

 hearth, which is one of the valu- 

 able features of the design. The 

 puddling furnace, the Siemens' 

 furnace, and the tube furnace all 

 belong to this type. See Furnace ; 

 Metallurgy. 



Revere, PAUL (1735-1818). 

 American soldier. He was born in 

 Boston, Mass.. and about the age of 

 twenty was an 

 officer in the 

 artillery. 

 Later he was 

 successively a 

 goldsmith and 

 a copper plate 

 engraver. He 

 took part in 

 the destruc- 

 tion of tea in 

 Boston H a r- 

 bour, Dec. 16, 1773, and in April, 

 1775, rode out by night from 

 Charleston to Lexington and other 

 places, arousing the minute men to 

 oppose the advance of the British 

 troops on Concord. This exploit 

 is the theme of Longfellow's poem, 

 Paul Revere's Ride. During the 

 war he rose to the rank of 

 lieutenant-colonel. He founded 

 the Revere Copper Co. at Canton, 

 Mass., in 1801, and died May 10, 

 1818. See True Story of Paul 

 Revere, C. F. Gettemy, 1905. 



Reverend (Lat. reverendus, wor- 

 thy of respect). Courtesy title be- 

 stowed on ministers of all denomi- 

 nations. In the Church of England 

 archbishops are styled. Most Rev- 

 erend, bishops Right Reverend, 

 and deans Very Reverend. Priests 

 and deacons and Nonconformist 

 ministers are styled Reverend 

 throughout the British Empire and 



Pan! Revere, 



American soldier 



6583 



in the United States. In Scotland, 

 the moderator of the General As- 

 sembly is styled Right Reverend, 

 and the principals of the universi- 

 ties, if in orders, Very Reverend. 

 In Roman Catholic countries priests 

 are styled Reverend Father, and 

 abbesses and prioresses Reverend 

 Mother. See Clergy. 



Reversing Layer. In astron- 

 omy, a layer or stratum in the sun's 

 atmosphere of mixed vapours, 

 which are at a lower temperature 

 than the actual solar surface. The 

 spectrum of the sun is ordinarily 

 crossed by a very large number of 

 dark lines. According to theory 

 they are produced by the absorp- 

 tive effect of incandescent gaseous 

 substances in the sun's atmosphere. 

 These gaseous materials are them- 

 selves glowing, but the lines they 

 produce are relatively dark against 

 the more brightly glowing back- 

 ground of the sun. 



On the occasion of an eclipse 

 the sun's brightness is cut off ; and, 

 as was first seen at the eclipse of 

 1870, the spectrum hitherto crossed 

 by dark fines becomes suddenly 

 covered with bright ones, as if the 

 dark lines had become reversed. 

 This phenomenon was attributed 

 by Professor Young to the presence 

 of the so-called reversing layer, the 

 thickness of which he estimated as 

 about 600 miles. Alternative ex- 

 planations of the absorption have 

 been offered by Sir Norman Lock- 

 yer, but the reversing layer's objec- 

 tive reality seems to have been de- 

 monstrated by a photograph taken 

 at Novaia Zemlia in the eclipse of 

 1896, and repeated at other 

 eclipses since. 



In meteorology, the term is also 

 used for a particular layer of the 

 earth's atmosphere. Though the 

 temperature of the earth's atmo- 

 sphere decreases regularly with 

 height for some eight to ten miles 

 above the earth's surface, at that 

 height a stratum is reached at 

 which temperature ceases to fall. 

 Above this layer, the terrestrial 

 reversing layer, the temperature 

 again falls regularly. See Fraun- 

 hofer Lines; Photosphere; Spec- 

 troscopy ; Sun. 



Reversion (Lat. revertere, to 

 turn back). Term used in English 

 law. It denotes the estate which 

 remains in a grantor after the de- 

 termination of a particular estate 

 granted by him. Thus A, the owner 

 in fee simple of a house, grants a 

 lease to B for 99 years. A is said to 

 have the reversion expectant on 

 the determination of the lease. If 

 B in his turn grants a sub-lease to 

 C for 21 years, B again has the 

 reversion expectant on the deter- 

 mination of the sub-lease. A's re- 

 version is called a freehold rever- 



REVIEW 



sion, and B's a leasehold reversion. 

 It is quite competent for A to grant 

 another lease, to come into force 

 after the expiration of B's lease, 

 and such a lease is called a rever- 

 sionary lease. 



Reversion to type is a biological 

 phenomenon to express the repro- 

 duction of an ancestral character- 

 istic. It may happen in two ways. 

 The individual may revert towards 

 an ancestor through the loss of 

 some power of development in the 

 germ-cell from which he sprang. 

 Secondly, he may reproduce an 

 ancestral characteristic which has 

 been missing in recent generations. 

 Reversions to type occur occasion- 

 ally when domestic varieties of ani- 

 mals are crossed experimentally, 

 but they also arise in pure-bred 

 individuals. Thus, in purely bred 

 races of pigeons of every kind 

 known in Europe, blue birds occa- 

 sionally appear, which is a rever- 

 sion. Archdall Reid regards feeble- 

 minded people as instances of re- 

 version to a pre-human mental 

 state, but the reversion here is not 

 complete, for while the imbecile 

 has lost his power of reason, he has 

 not regained the instincts which 

 would guide him otherwise. See 

 Atavism ; Biology ; Heredity. 



Revetment. Term used in mili- 

 tary engineering to indicate any 

 material which is used as a retain- 

 ing wall to support earth at a 

 steeper slope than the natural angle 

 at which it will stand unsup- 

 ported. The natural angle at which 

 earth will stand is about 45 deg., 

 and consequently revetment is re- 

 quired in the case of most entrench- 

 ments and other field works. Grass 

 sods built into a wall and secured 

 by pickets make an effective revet- 

 ment, but generally are not avail- 

 able in sufficient quantity. Sand- 

 bags can be similarly employed or 

 stakes driven into the ground and 

 interwoven with brushwood, wire 

 netting, expanded metal, etc., or 

 planks placed behind them, but the 

 latter are liable to become danger- 

 ous missiles, if high explosive shells 

 burst near them. Canvas stretched 

 behind and secured to a row of 

 stakes is also effective, whilst the 

 various forms of gabions are 

 largely employed. Hurdles make a 

 good revetment for a long, straight 

 run, and fascines are used as a 

 revetment for special purposes to 

 which they are adapted, particu- 

 larly for steps. See Entrenchment , 

 Fascine ; Fortification ; Gabion. 



Review of Reviews, THE. Brit- 

 ish monthly periodical. It was 

 founded Jan., 1890, by W. T. 

 Stead (q.v. ), to provide a synopsis 

 of the best articles in the reviews 

 and magazines of the month, to- 

 gether with a survey of current 



