DRY POINT 



27O1 



DUALISM 



Dry Point. Process of etching. 

 It is closely akin to line engraving, 

 in the preliminary stages of which 

 it was often used, especially in out- 

 lining the general disposition of a 

 subject. The tool is a steel rod 

 tapering at one or both ends to a 

 strong, fine, sharp point. With this 

 the etcher draws with a firm hand, 

 the point scratching a line of ex- 

 quisite sensitiveness on the copper 

 plate, and raising, as it goes along, 

 a very distinct burr on the sides of 

 the furrow, which lends particular 

 value to early prints from the plate. 

 Dryptosaur (Gr. dryptein, to 

 tear ; sauros, lizard). Extinct N. 

 American reptile of the genus 

 Dryptosaurus, alternatively called 

 Laelaps. It was a carnivorous, 

 beast-footed dinosaur, living in 

 Montana in Upper Cretaceous 

 times, and allied to the English 

 megalosaur. It was 20 ft. long, 

 rapacious and sharp-toothed; it 

 used the hind limbs and tail in 

 kangaroo fashion. See Dinosaur. 



Dry Rot. Diseased condition of 

 timber due to the ravages of cer- 

 tain species of fungi, especially 

 Merulius lachrymans. This fungus 

 rapidly consumes the woody cells 

 and fibres, the affected parts crum- 

 bling to a brownish powder upon 

 exposure to a dry atmosphere. A 

 certain degree of moisture is essen- 

 tial to the growth of the fungus, and 

 is visible where it spreads its lace- 

 like film over wood confined within 

 a damp and stagnant atmosphere. 

 The popular term serves to distin- 

 guish this condition from wet rot, a 

 kind of putrefaction occurring in 

 wood exposed to the weather. 



A single plant of Merulius 

 lachrymans puts forth millions of 

 reproductive spores, which, being 

 of microscopic size, may be borne 

 about by the air, or conveyed im- 

 perceptibly from infected to sound 

 timber by a saw ; or the disease 

 may be propagated by the disper- 

 sion of infected sawdust, or by the 

 creeping of the fungus from one 

 piece of timber to another, even 

 when the pieces are separated by 

 some material from which the 

 fungus can derive no sustenance, 

 but which it will use as a bridge, 

 such as brick or stone. The com- 

 mon idea that the fungus eats 

 away the interior of beams which 

 outwardly appear sound is pro- 

 bably erroneous. Thus, in the old 

 roof of Westminster Hall some of 

 the beams and rafters were hol- 

 lowed to mere shells, but it was 

 found that the damage was due 

 to a boring beetle. Dry rot, it is 

 believed, cannot develop (though 

 it may long remain latent) in wood 

 to which air-currents have free 

 access, and from which moisture 

 is excluded. 



Conformably to this assumption, 

 architects and builders are legally 

 required to provide effective venti- 

 lation and otherwise prevent damp- 

 ness by inserting damp - proof 

 courses, concreting foundations, 

 and forming dry areas (see Brick- 

 work; Building). Steeping the 

 wood in corrosive sublimate has 

 been recommended as an addi- 

 tional precaution against dry rot. 

 The dry rot of oak-built ships is 

 usually due to another species of 

 fungus, Poria hybrida. 



Drysaltery. Term applied to 

 the business of a drysalter or the 

 articles sold by him. These consist 

 of heavy chemicals (borax, salt, 

 soda, sulphur, etc.), dye-stuffs 

 (alkanet, indigo, etc.), gums 

 (arabic, shellac, kauri, resin), oils 

 (paraffin, linseed oil, boiled oil, tur- 

 pentine), and crude drugs (linseed, 

 senna, Epsom salt, Glauber's salt, 

 etc.). Drysalters also sell pickles, 

 preserved meat, and sauces. 



D.S.C. Abbrev. for Distin- 

 guished Service Cross (q.v.) (for- 

 merly Conspicuous Service Cross). 

 D.Sc. Abbreviation for Doctor 

 of Science. 



D.S.M. Abbrev. for Distin- 

 guished Service Medal (q.v). 



D.S.O. Abbreviation for com- 

 panion of the Distinguished Service 

 Order (q.v.). 



Dual. Grammatical form origi- 

 nally used in some languages to 

 express the idea of things naturally 

 thought of in pairs, as the eyes and 

 feet. It was then extended to other 

 objects associated in twos (two 

 men, two books). It is found in 

 Sanskrit, ancient Greek, Arabic, 

 and Hebrew, and traces of it occur 

 in Anglo-Saxon. 



Duala. Town and district of 

 Cameroons, W. Africa, The town 

 is situated on the Cameroons river 

 about 18m. from the sea, and is the 

 chief seaport of Cameroons. Duala 

 proper, i.e. the port and European 

 quarters, occupies the site of the 

 former Bell Town. Akwa is a large 

 native centre and Dido the residen- 

 tial quarter for the native clerks 

 and workmen employed at the port. 

 These three towns, known collec- 

 tively as Duala, represented the 

 headquarters of the three native 

 chiefs at the time of the German 

 occupation in 1884. 



Duala occupies a position of 

 great importance with respect to 

 maritime trade in W. Africa. The 

 Northern Riy. runs from Bona- 

 beri, opposite Duala, northward, 

 and will eventually be prolonged to 

 a poiat on the Shari river, probably 

 Fort Lamy. The Midland Riy. 

 leaves Duala in a southerly direc- 

 tion and runs to the Njong river, 

 whence it will be continued to 

 Wesso, on the navigable Sanga 



tributary of the Congo, in the one 

 direction, and to Bangui, on the 

 Ubangi river, in the other. Duala 

 will thus become the main outlet 

 for French Equatorial Africa and 

 the Lake Chad region. There is an 

 extensive trade in palm oil and 

 palm kernels, cocoa, and rubber. 

 Duala is now in the French sphere. 

 It was captured by a combined 

 British and French force on Sept. 

 27, 1914. Pop. of district, 77,000, 

 and of town 22,000. See Cameroons, 

 Conquest of; also illus. p. 1612. 



Dual Control. Any system of 

 controls for engine and aeroplane, 

 whereby either the pilot or pas- 

 senger can operate them. It is 

 principally employed in the instruc- 

 tion of pupils. Two sets of rudder 

 and control levers are installed, and 

 these are interconnected so that 

 the instructor can correct the faults 

 of the pupil. See Airmanship. 



Dual Ignition. Arrangement 

 by which two forms of ignition 

 apparatus are fitted to an engine. 

 One system is by accumulator and 

 coil for starting purposes, and by 

 magneto for the subsequent opera- 

 tion. The term is sometimes applied 

 to the system of fitting two spark- 

 ing plugs to the engine cylinder in 

 order to produce two sparks simul- 

 taneously and thus facilitate the 

 ignition of the explosive mixture. 



Dualism (Lat. dualis, contain- 

 ing two). The assumption of two 

 principles, as opposed to monism, 

 the assumption of one. It may 

 be applied to man (anthropologi- 

 cal), to God (theological), to the 

 world and existence (cosmological, 

 metaphysical). Anthropological 

 dualism regards man's body and 

 soul as two distinct existences ; 

 theological dualism assumes two 

 first principles, a good and a 

 bad, eternally in conflict ; cosmo- 

 logical dualism lays down two 

 original substances or entities, 

 mind and matter, thinking sub- 

 stance and extended substance, of 

 which everything is composed. 



In the ancient philosophies dual- 

 ism appeared as the opposition of 

 matter and form, later as a contest 

 between objectivity and subjec- 

 tivity, the last attempt to reconcile 

 them being that of neo-Platonism. 

 Descartes was the first of modern 

 philosophers to substitute for this 

 the dualism of mind and matter, 

 and from his time the question how 

 their relation to each other as mani- 

 fested in experience is to be inter- 

 preted has engaged the attention 

 of thinkers without any satisfac- 

 tory or generally accepted explana- 

 tion being reached. The reaction 

 against idealism, which amounted 

 to an abolition of dualism, has led 

 to the reassertion of the latter by 

 some philosophical writers. 



