PEN 



tViofe of any other ftringed inftrument played with the 

 naked fingers ; that it is more touching and proper to ex- 

 prefs tendernefs and grief than other affections of the heart ; 

 that the ilrings muft be moderately ftruck, otherwife the 

 mufic would be as confufed as on the harpfichord or piano- 

 forte without dampers ; and, laftly, the author of the article 

 (the comte de Hoghenfki) fays, that the Irilh, of all the 

 people in the world, are thofe reputed to perform the bcft 

 on the harps of their country. 



PEDILUVIUM, in Medicine, from pedes, the feet, and 

 lavo, I izua/h, a bathing or immerfion of the feet in warm 

 water. 



The older praftitioners refcrted to the pediluvium in a 

 variety of difeafes upon hypothetical principles ; conceiving 

 that, by drawing the blood into the vefTels of the feet, it 

 rcheved diftant organs, as the head or lungs, which were 

 overcharged by a ilate of inflammation in congeftion : 

 hence it was recommended in apoplexy, pleurify, and 

 other topical affections of diftant parts. This doctrine of 

 revulfion, however, as applied to the operation of the pedi- 

 luvium, is more quellionablc than under any other appHca- 

 tion of it ; for as, like the general wann-bath, it fome- 

 what accelerates the general circulation, it muft be a doubt- 

 ful remedy in cafes where the motion of the heart and arteries 

 is already too great. 



The operation of the pedikunum is, in faft, fimply that 

 of a partial warm-bath ; and its ufe is at prefent limited 

 to thofe diforders in which that more general remedy is 

 indicated ; being a more practicable and eafy expedient, 

 though neceffarily much lefs effectual in its influence. The 

 moft valuable and common application of the pediluvium - 

 is at the onfet of febrile difeafes, while a certain degree of 

 chillinefs is prefent. Ufed in this ftate previous to going 

 to bed, it contributes, by moderately exciting the heart 

 and arteries, to equalife' the circulation, and determine the 

 blood to the furface, whence a flight diaphorefis often fol- 

 lows its ufe under thefe circumftances. Thus the 

 attack of a commencing catarrh or rheumatifm is often 

 warded off by the ufe of pediluvium, aided by other proper 

 means ; and to this kind of treatment its operation is pro- 

 bably to be limited. In the more advanced ftage of febrile 

 difeafes, efpecially when there is delirium, or a general heat, 

 its advantages are very problematical. 



PEDRICK Island, in Geography, a townfliip of Ply- 

 mouth county, in Maffachufetts, having 7 perfons. 



PEELIISfG, 1. 2, r. 203. 



PEEPEC, a townfhip of Ohio, in Rofs county, contain- 

 ing 670 perfons. 



PEGYPSENT, a town of Maine, in the county of 

 Cumberland, having 805 inhabitants. 



PELHAM, 1. 3, r. 1185 ; 1. 7, r. 998. 



PEMBROKE, in America, 1. 3, r. 2051. Col. 2, 

 1. 2, r. 1153. 



PENCADER, a hundred of Newcaftle county, in the 

 diftritt of Delaware, having 1865 perfons. 



PENDLETON, 1. 4, r. 4239 inhabitants, of whom 202 

 are flaves ; 1. 6, r. 22,897 ; 1. 23, r. 3485. Col. 2, 1. I, 

 r. 2940 ; 1. 2, r. 346. 



PENDULUM, col. 10, 1. 16, add— The lateft and 

 moft correct experiments that have been made for deter- 

 mining the length of the pendulum vibrating feconds are 

 thofe of captain Kater. Thefe experiments were performed 

 with a pendulum conftructed on the following principle : 

 In illuftrating (his principle he ftates, as a known fa£t, 

 that the centres of fufpeniion and ofcillation are reciprocal ; 

 or, in other words, that if a body be fufpended by its 

 centre of ofcillation, its former point of fufpenfion becomes 



PEN 



the centre of ofcillation, and the vibrations in both pofitions 

 will be performed in equal times. As the diftance of the 

 centre of ofcillation from the point of fufpenfion depends 

 on the figure of the body employed, if the arrangement of its 

 particles be changed, the place of the centre of ofcillation 

 will alfo fuffer a change. Suppofe then a body to be furnifh- 

 ed with a point of fufpenfion, and another point on which 

 It may vibrate, to be fixed as nearly as can be eftimated in 

 the centre of ofcillation, and in a hne with the point of 

 fufpeniion and centre of gravity. If the \-ibrations in each 

 pofition (hould not be equal in equal times, they may be 

 readily made fo, by fliifting a moveable weight, with which the 

 body is to be furniflied, in a line between the centres of fuf- 

 penfion and ofcillation ; when the diftance between the two 

 points about which the vibrations were -performed being 

 meafured, the length of a fimple pendulum, and the time of 

 Its vibration, will at once be known, uninfluenced by any 

 irregularity of denfity or figure. This principle being 

 adopted for the confiruction of the pendulum, the next 

 objett of importance is to felect a mode of fufpenfion equally 

 free from objection. For this purpofe a knife-edge was 

 preferred, and the grounds of preference are briefly ftated. 

 The pendulum is formed of a bar of plate brafs, an inch 

 and a half wide and one-eighth of an inch thick. Through 

 this bar two triangular holes are made, at the diftance of 39,4 

 inches from each other, to admit the knife-edges. Four 

 ftrong knees of hammered lirafs, of the fame width as the 

 bar, {i\ inches long, and three-quarters of an inch thick, are 

 firmly fcrewed by pairs to each end of the bar, in fuch a 

 manner, that when the knife-edges are paffed through the 

 triangular apertures, their backs may bear fteadily againft 

 the perfectly plane furfaces of the brafs knees, which are 

 formed as nearly as poffible at right angles to the bar, 

 which is cut of fuch a length, that its ends may be fliort 

 of the extremities of the knee -pieces about two inches. 

 Two flips of deal 1 7 inches long, and of the fame thick- 

 nefs as the bar, are inferted in the fpaces thus left between 

 the knee -pieces, and are firmly fecured there by pins and 

 fcrews. Thefe flips of deal are only half the width of the 

 bar ; they are ftained black, and in the extremity of each a 

 fmall whale -bone point is inferted, for the purpofe of indi- 

 cating the extent of the arc of vibration. A cylindrical 

 weight of brafs, in diameter three inches and a half, and an 

 inch and a quarter thick, and weighing about 2 lbs. 7 oz., 

 has a rectangular opening in the direction of its diameter, 

 to admit the knee-piece of one end of the pendulum. This 

 weight being pafled on the pendulum, is fo thoroughly 

 fecured there by means of a conical pin fitting an opening 

 made through the weight and knee-pieces, as to render any 

 change of pofition impoffible. A fecond weight of about 

 feven ounces and a half is made to flide on the bar near 

 the knife-edge at the oppofite end ; and this weight mav 

 be fixed at any diftance on the bar by two fcrews with 

 which it is furnifted. A third weight, or Aider of four 

 ounces, is moveable along the bar, and is capable of nice ad- 

 juftment by means of a fcrew fixed to a clamp, which clamp 

 is included in the weight. This Aider is defigned to move 

 near the centre of the bar ; and it has an opening, through 

 which may be feen divifions, each equal to one-tv%-ent!eth of 

 an inch, engraved on the bar ; and a line is dr.'.v.n on the 

 edge of the opening to ferve as an index for determining the 

 diilance of the Aider from the middle of the bar. The 

 knife-edges are made of that kind of ileel prepared in 

 India, and called wootz. Their form is triangular, and their 

 length an inch and three-quarters. They were ground on a 

 plane tool, fo as to enfure their having a perfectly ftraight 

 edge. They were then carefully finilticd on a plane green 

 4 G 2 hone, 



