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PHYTOLOGY PIB-CORN. 



circulation of the blood was a great step, but it in- 

 duced his successors to attempt to explain life by 

 mere mechanical and hydraulic principles. Stalil 

 considered the soul as the cause of life and its phe- 

 nomena ; but Haller made an entirely new epoch, 

 by the theory of the irritability of the fibre, which 

 was made the basis of many systems ; even Brown's 

 theory of life, as arising from the irritability of the 

 organization, and the influence of external things, is 

 to be deduced from this source. The progress of 

 chemistry and philosophy gave rise to another mode 

 of treating physiology, the former by analyzing the 

 simple substances of the body, the latter by the 

 faithful investigation of what is within and what 

 without the limits of the reasoning faculty, thereby 

 banishing a number of untenable theories. 



PHYTOLOGY (from $uro>, plant, and Xoy, sci- 

 ence) ; a word not unfrequently used for botany by 

 the Germans of late, they considering it more cor- 

 respondent than botany to the denominations of the 

 kindred sciences, zoology and mineralogy, and better 

 adapted to the more elevated character which the 

 science has received of late, since the whole nature 

 of plants has been more thoroughly studied than 

 formerly. See Plants. 



PIA MATER, in anatomy ; a thin membrane 

 immediately investing the brain. 



PIANO (Italian) ; soft, slow '; used in music in 

 contradistinction to forte. Pianissimo ; the super- 

 lative of piano. 



PIANO-FORTE ; a musical stringed instrument, 

 the strings of which are extended over bridges rising 

 on the sounding-board, and are made to vibrate by 

 means of small, covered hammers, which are put in 

 motion by keys, and where a continued sound is not 

 contemplated, their sound is dampened immediately 

 after the touch of the keys by means of leathern 

 dampers. The piano has superseded the harpsichord 

 principally owing to its greater strength, fulness 

 and duration of tone. The strength of the tones 

 has also been increased by increasing the number of 

 the strings for each tone. There are usually three 

 strings for each tone. The hammers usually strike 

 the strings from below ; but, of late, instruments 

 have been made in Vienna, called Kapotasto, in 

 which the hammers strike the strings from above, 

 and thereby produce a stronger tone. A change or 

 prolongation of tone is produced by means of pedals : 

 only a few, however, are at present used. Formerly, 

 the clavichord and the spinnet supplied the place of 

 the piano-forte; and all three instruments possess 

 the advantage that a single player on the same can 

 produce a complete harmony, and the most rapid 

 and difficult series of tones can be executed by means 

 of a simple mechanism, on which account these in- 

 struments greatly facilitate the study of harmony. 

 To the harpsichord the piano-forte is inferior in this 

 single particular, that, in the former instrument, the 

 touch has a great influence on the character of the 

 tones, while, in the case of the piano-forte, they are 

 in a manner prepared beforehand. This instrument 

 is usually tabular in shape (these are commonly of a 

 comparatively weak tone), or spinnet-formed. Those 

 in the shape of a long spinnet (grand piano-fortes) 

 are used as concert instruments, and have the great- 

 est compass and strength. The grand piano-forte 

 is one of the noblest and most elegant musical in- 

 struments. The common compass of piano-fortes at 

 present is six octaves rising from the lowest F. 

 There are also instruments of this class in an upright 

 form ; for example, Dietanaklasis, which, however, 

 are less in use. The piano-forte was invented by 

 Christian Gottlieb Schroecler of Hohenstein, in Sax- 

 ony, born in the beginning of the eighteenth century 

 (about 1717, in Dresden). It has been gradually 



improved, till it has become one of the most impor- 

 tant instruments in all musical entertainments. In 

 strength and firmness, the English piano-fortes excel 

 all others. They are, however, comparatively diffi- 

 cult to use, and are very expensive. 



PIARISTS ; fathers of the pious schools (scltol- 

 arum piartim) ; the members of a religious order, 

 who, in addition to the three usual monastic vows, 

 took also a fourth, namely, to devote themselves to 

 the gratuitous instruction of youth. (See Monastic 

 Vows, and Orders, Religious'). This order was in- 

 stituted at Rome, in the beginning of the seventeenth 

 century, by Joseph Casalanza (died 1648), a Spanish 

 nobleman, and confirmed by the pope in 1621. In 

 1690, it was rewarded for its useful labours, by the 

 most important privileges of the mendicant orders. 

 The piarists are, like the Jesuits, a secular order, 

 subject to rules. They also resemble the Jesuits in 

 their costume, and in their devotion to the service 

 of the church and to education, and have been the 

 rivals of that order from the time of their institution. 

 They soon spread themselves through the Catholic 

 countries, particularly in the Austrian dominions, 

 and became numerous and powerful, without sub- 

 jecting themselves to the charge of ambitious views, 

 and without meddling in political matters, as the 

 Jesuits did. Many gymnasia and schools in Hungary 

 and Poland are still under their direction. In Bo- 

 hemia, Moravia, Silesia and Austria, they have some 

 respectable colleges, and their services in the cause 

 of education have undeniably been great. 



PIASTER. (See Coin, division Spain and Tur- 

 key.) The Turkish piaster varies much in value. 



PIAZZA, in architecture, is a portico, or covered 

 walk, supported by arches ; and all walks, with 

 porticoes around them, are piazzas. 



PIAZZI, GIUSEPPE, director-general of the obser- 

 vatories at Naples and Palermo, was born at Ponte, 

 in the Valteline, in 1746 ; in 1764, entered the order 

 of the Theatines at Milan, and studied at Milan, 

 Turin and Rome, under Tiraboschi, Leseur and Bec- 

 caria. In 1770, he was appointed professor of ma- 

 thematics at the new university in Malta, on the abo- 

 lition of which he returned to Italy, and, in 1780, 

 became professor of the higher mathematics at Pal- 

 ermo. Having induced the viceroy to establish an 

 observatory there, Piazzi went to England and France 

 to purchase the necessary instruments. The obser- 

 vatory was completed in 1789, and is described in 

 Piazzi's Delia Specola astronomica de' Registudj di 

 Palermo, 1792 94. His first observations were 

 published in 1792. He soon after began his cata- 

 logue of stars, and dedicated the first, contain ing 

 6784 stars, to the institute at Paris. January 1, 

 1801, Piazzi discovered the planet Ceres, in com- 

 memoration of which the king of Naples wished to 

 strike a gold medal in his honour ; but Piazzi pre- 

 ferred that the money should be applied to the pur- 

 chase of instruments for the observatory. In 1814, 

 he completed his second catalogue, containing 7646 

 stars. He had also been occupied in the reforma- 

 tion of the system of weights and measures in Sicily. 

 The observation of comets he always considered as 

 useless. In 1817, the king called him to Naples to 

 examine the plan of the new observatory there ; and 

 his last years were chiefly devoted to the subject of 

 public education in Sicily. He died July 22, 1826. 

 His Lezioni elementari di Astronomia were publish 

 ed at Palermo in 1817. 



PIB-CORN, OR HORNPIPE; a Welsh instru- 

 ment, consisting of a wooden pipe, with holes at the 

 sides, and a horn at each end, the one to collect the 

 wind blown into it by the mouth, and the other to 

 convey the sound as modulated by the performer. 

 This instrument is so common in Wales, that the 



