PERCUSSION 



PERCY 



43 



Percussion, in Medicine, is the method of 

 eliciting sounds by tapping or gently striking the 

 Mirface of the body ; its object being to determine 

 by the nature of the sound the comparative density 

 of the subjacent parts. This means of diagnosis 

 wa> lirst employed by Auenbrugger in the middle 

 of the 18th century, and it was afterwards adopted 

 by Corvisart in the investigation of heart diseases ; 

 but its value was not fully appreciated till Laennec 

 made the diseases of the chest his peculiar study ; 

 and since his time its application and various uses 

 have l>een extended by the labours of Piorry, 

 Hughes Bennett, and other physicians. 



Percussion is chiefly employed in the diagnosis 

 of diseases of the lungs, heart, and abdominal 

 organs. It mav be direct (or, as some writers 

 it-nil it, immediate), or it may be mediate. In 

 the former case, the part to l>e examined is struck 

 with the ends of the first three fingers set close 

 together on the same level, or with a small hammer 

 tipped with india-rubber ; while in the latter, 

 which is now almost universally adopted, a flat 

 body is placed upon the chest, or other part to be 

 examined, and is then struck by the fingers or 

 hammer. The flat intervening body is termed a 

 Pleximeter (from the Gr. plexis, 'a blow," and 

 metron, 'a measure'). The instrument usually 

 sold as a pleximeter is a flat oval piece of ivory, 

 but the left index or middle finger of the physician, 

 with it- flat surface fitted accurately to tne part to 

 lie examined, acts equally well. The force of the 

 stroke on the pleximeter whether the stroke be 

 mad"- with the lingers or the hammer must vary 

 according as it is desired to elicit the sound from a 

 superficial or a deep-seated part. The surface to 

 be percussed should lie exposed, or, at most, only 

 covereil with one layer of clothing ; and the blow 

 should fall perpendicularly on the pleximeter. 

 When percussion U made over a considerable 

 cavity filled with air as the stomach or intestines 

 a hollow, drum-like, or (as it is usually termed 

 l>y medical writers) a tympanitie sound is pro- 

 duced. When any part of the surface of the chest 

 i- -truck below which there is a considerable depth 

 of healthy lung-tissue, consisting of small cells 

 filled with air, a clear sound, less loud and hollow 

 than the tympanitic sound, and termed the /ml 

 ni'iiiiiril percussion note, depending partly on the 

 vibrations of air in the lung-cells, and partly on 

 the vibrations of the walls of the chest, is evolved. 

 When the subjacent substance is solid (as the 

 heart, liver, or spleen) or fluid (as when there is 

 effusion into a closed sac) the sound is ilnll in 

 proportion to the density ami want of elasticity of 

 the part struck. Important information is also 

 gained by attending to the varying degree of 

 resistance experienced by the fingers during per- 

 M ion over different parts of the surface. The 

 first thing that must be acquired in order to make 

 lTeii.iiiu useful in the diagnosis of disease is an 

 accurate knowledge of the sounds elicited from the 

 different parts in their normal condition. When, 

 for example, the healthy pulmonary percussion 

 note is known, increased resonance of the walls of 

 the chest will indicate a dilatation of the air-cells 

 (or Pulmonary Kniphy*i-nia), while various degree* 

 of dullness will afford evidence of such morbid 

 changes as the effusion of fluid into the pleura 

 ( Hydrothorax), or inflammatory solidification of 

 the lung tissue (the Hepntisation of Pneumonia), 

 or tuliercular deposition. The use of percussion 

 in relation to diagnosis is further shown in the 

 articles PERICARDIUM and PI.KI'RISV. Diagnosis 

 by Auscultation (q.v. ), directly anil by means of 

 the Si"tliocope (q.v.), is often used in connection 

 iih |>ercnssion. 



Percussion <'apH are small copper cylinders, 

 closed at one end, for conveniently holding the 



detonating powder which is exploded by the act of 

 percussion in percussion-arms. See FULMINATES ; 

 also FIREARMS, Vol. IV. p. 639. 



Percussion, CENTRE OF. See CENTRE OF 

 PERCUSSION. 



Percy, a noble northern family, famous in the 

 history of England for five hundred years. Its 

 founder, William de Percy, came with the Con- 

 queror to England, and was rewarded with lands 

 in Hampshire, Lincolnshire, and Yorkshire among 

 the last being Topcliffe and Spoftbrth, long the 

 chief seats of the house. The male descendants 

 liecame extinct with the death of the third baron, 

 and the representation of the house devolved upon 

 his daughter Agnes, who married Josceline of 

 Louvain, brother-in-law of King Henry I., on 

 the condition that he assumed the name of 

 Percy. Their youngest son, Richard de Percy, 

 then head of the family, was one of the chief 

 barons who extorted Afagna Charta from King 

 John, and the ninth feudal lord, Henry de Percy, 

 gave much aid to Edward I. in the subjugation of 

 Scotland, and was made governor of Galloway. 

 The latter was driven out of Turn berry Castle by 

 Robert Bruce, and was rewarded by Edward if. 

 with the empty honour of Bruce's forfeited earldom 

 of Carrick, and the governorship of the castles of 

 BamlMirough and Scarborough. In 1309 he obtained 

 by purchase from Bishop Antony Bek the barony 

 of Alnwick, the chief seat of the'family ever since. 

 His son, Henry de Percy, defeated and captured 

 King David II. of Scotland at the battle of Neville's 

 Cross (1346); his grandson fought at Crecy ; his 

 great-grandson, the fourth Lord Percy of Aln- 

 wick, was marshal of England at the corona- 

 tion of Richard II., and was created the same 

 day Earl of Northuml>erland. Henry, eldest son 

 of the last, was the famous Hotspur whom the 

 dead Douglas defeated at Otterburn (1388), ami 

 who himself fell at Shrewsbury (1403) fighting 

 against King Henry IV. His brother, Thomas 

 Percy, Earl of Worcester, was executed immedi- 

 ately after the battle. Their father, who had 

 turned against Richard II., and helped Henry of 

 Lancaster to the throne, was dissatisfied with 

 Henry's gratitude, and with his sons plotted the 

 insurrection which ended in Shrewsbury fight. 

 Later he joined Archbishop Scroope's plot, and 

 fell at Bramham Moor (1408), when his honours 

 were forfeited on attainder, but restored in 1414 

 to his grandson Henry, the second earl, from which 

 day the Lancastrian loyalty of the family never 

 wavered. Henry became High Constable of Eng- 

 land, and fell in the first battle of St Albans 

 (1455). His son Henry, the third earl, fell at 

 Towton ( 1461 ), and it was his brother, Sir Ralph 

 Percy, who comforted himself as he lay bleeding 

 to death on Hedgley Moor (1464), that he had 

 'saved the bird in his bosom.' The title ami 

 estates were now given to Lord Montagu, a brother 

 of Warwick, the king-maker, but in 1469 Henry, 

 the son of the third earl, subscribed an oatli of 

 allegiance to Edward IV., and was restored. He 

 was murdered at his Yorkshire house of Cock- 

 lodjje, in 1489, in- an outburst of popular fury 

 against an extortionate subsidy of Henry VII. 

 The sixth earl, Henry-Algernon, in youth had been 

 the lover of Anne Boleyn, and was forced against 

 his will to marry a daughter of the Earl of Shrews- 

 bury. He died childless in 1537, and, as his brother 

 Sir Thomas Percy had been attainted and executed 

 for his share in the Pilgrimage of Grace, the title 

 and honours were forfeited, and the title of Duke 

 of Northumberland was conferred by Edward VI. 

 upon John Dudley, Earl of Warwick, who in turn 

 was attainted and executed under Mary in 1553. 

 That queen in 1557 granted the earldom to Thomas 



