Pylon. In aeronautics, an ar- 

 rangement of struts for the sup- 

 port of certain bracing wires in an 



Pylon of an aeroplane, indicated at A 



aeroplane (q.v.). The term is used 

 for the support for the upper bracing 

 wires of a monoplane wing, and 

 for similar wires bracing an over- 

 hanging top wing on biplanes. The 

 pylon bracing or structure on aero- 

 plane wings is necessary when the 

 machine has landed, in order to 

 support the weight of the wings. 

 Otherwise the latter would collapse 

 unless specially strengthened spars 

 were provided, as is sometimes the 

 case. It is also the name given to 

 the towers used on an aerodrome to 

 mark the course for aeroplane races. 



Pylorus (Gr. pyle, gate ; ouros, 

 warder). Distal or intestinal 

 aperture of the stomach. It is sur- 

 rounded by a ring of muscular 

 fibre which, following a meal, is in 

 a state of contraction, thus retain- 

 ing the food in the stomach for the 

 process of digestion. At varying 

 intervals the muscular fibres relax, 

 and food is permitted to pass on- 

 wards into the intestine for further 

 digestion, 



Pylos. Town in the S.W. of 

 Messenia, ancient Greece, about 

 60 m. from Sparta. In legendary 

 times the venerable Nestor, of the 

 Homeric poem, was its king. In 

 425 B.C. it was seized by the Athen- 

 ians in the Peloponnesian War, 

 while in the adjacent Bay of 

 Navarino the Turkish fleet was 

 defeated by the allied fleets of the 

 British, French, and Russians in 



1827, a victory which secured the 

 in dependence of Greece. The 

 modern Pylos or Navarino (q.v.) 

 stands at the S. end of the bay. 



Pym, JOHN (1584-1643). English 

 statesman. He was born at Bry- 

 more, Somerset, and educated at 

 Pembroke College (then Broad- 

 gates Hall), Oxford, afterwards 

 becoming a student at the Inner 

 Temple, though he was never 

 called to the bar. In 1614 he 

 became member of Parliament for 

 Calne, and in 1625 member for 

 Tavistock. Already a prominent 

 member of the parliamentary 

 party that was coming into conflict 

 with the crown, he was one of the 

 managers of 

 the impeach- 

 ment of Buck- 

 ingham in 

 1626, one of 

 the chief sup- 

 porters of the 

 Petition of 

 Right in 

 1628, and in 

 1629 an ener- John Pym. 



getic opponent English statesman 

 of the tonnage and poundage pro- 

 posals. Between 1630 and 1640 he 

 was engaged in schemes for the 

 settlement of Connecticut. 



Pym was in effect the leader of 

 the Short Parliament of 1640, took 

 a principal part in the impeach- 

 ment of his whilom friend Straf- 



PYORRHOEA 



posal to check the royal powci 

 by making ministers responsible 

 to Parliament. He was one of 

 the five members (q.v.). Pym died 

 Dec. 8, 1643, having been made 

 master of the ordnance a month 

 earlier. See Statesmen of the 

 Commonwealth, J. Forster, 1840. 



Pyorrhoea. Disease of the 

 tissue surrounding the necks of 

 the teeth. In the nature of a re- 

 action against an external irritant 

 (tartar and micro-organisms), its 

 characteristic symptom is the 

 exudation of matter from the gums 

 around the necks of the teeth. 

 Associated with this the gums are 

 inflamed, the bony socket is 

 softened, and the teeth become 

 loose, eventually falling out if the 

 disease continues sufficiently long. 



The disease commences at the 

 gum margins, which become red 

 and swollen. At a later but 

 variable stage the gum loses its 

 connexion with the root of the 

 tooth towards the neck, and 

 exudation of matter starts from 

 the part of the gum which has 

 become separated from the roots. 

 Covering the part of the teeth 

 from which the gum has separated, 

 there is a coating of tartar which 

 gradually tends to form farther 

 down the root of the tooth, and 

 thus progressively to deepen the 

 trough between the gum and the 

 root. Together with these changes 



ford in that year, and had a share the destruction and absorption of 

 in the Grand Remonstrance of the bony socket are progressive. 



The cause of pyorrhoea is lack of 

 cleanliness at the necks of the teeth, 



Remonstrance of 

 1641, when he 

 tpl first put for- 

 i ward the pro- 



Pygmy. Left, group of pygmy dancers with two Bantn women of normal height ; right, family 

 oi the Mambuti tribe, from the Albert Nyanza. Inset, bead of a pygmy woman 



induced by stagnation, 

 predisposed to by lack 

 of function. This lack 

 of function may arise 

 either from the ha- 

 bitual consumption of 

 foods which do not 

 stimulate efficient 

 mastication and the 

 self-cleansing pro- 

 cesses of the mouth, 

 or because opposing 

 teeth are absent. 



As the teeth are 

 normally coated with 

 mucus, and as this 

 mucus is liable to 

 become impregnated 

 with lime salts if it 

 stagnates continually 

 at the necks of the 

 teeth, it is of special 

 importance to eat food 

 of such a nature as 

 will disintegrate this 

 mucus, before it has 

 adhered to the necks 

 of the teeth suffi- 

 ciently long to favour 

 the deposition of 

 tartar. The foods 

 which precipitate 



