PIETISII. 10 PIFFERAM. divines. When the inevitable reaction came it took form in favor of a rcliyiou of feeling and good works, or of the heart and life. Johann Arndt (1555-l(i21), Johann Valentin Andre.-e ( 158(j-lG54), both Lutherans, and Johannes Coe- cejus ( lOO.SGO), a Calvinist. may bo rejrarded as forerunners of Pietism. But its full develop- ment is to be ascribed to Philipp Jakob Spener (q.v.) and his friends and disciples, particularly the Leipzig Docents. Paul Anton, J. K. Schade, and August Hermann Francke. Driven from Leipzig by the opposition of the older school of theologians. Franeke and Anton found a refuge, through Spener's influence, in the newly founded University of Halle, and under their lead and that of their associates, Joachim Justus Breit- haupt and Hermann Lange. Halle became the centre of the movement and a source of new religious life in Germany. Pietism also became dominant in the imiversities of Ki'migsberg, Giessen. and Marburg, and from Xorth Germany spread to the south, where its head was Johann Albrecht Bengel, and even to other lands. Ulti- mately it went to excess, fantastic doctrines and fanatical practices came to prevail, and the rationalism of the eighteenth century was the inevitable and healthful reacticm. For further details, see the article German Theology, sec- tion The Period of Pietism ; see also the bio- graphical notices of Spener, Franeke. Bengel. and the other leaders. Histories of Pietism have been written by Schmidt (Xiirdlingen, 1803) ; Tholuek (Berlin. 18(1.') I: Heppe. treating particularly of the movement in the Xetherlands (Leipzig, 1870); and Kitschl ( lionn, lS80-8(i). Consult, also, Renner. Lebeiisbihler aus dcr Pietixtenzeit (Bremen, 18S(i) ; Hubener. Pietixmus fieschicht- lieh und dofiinatinch fiischildert (Zwickau, 1901). PIET PAALTJENS, pet i);llt'ycns. The pseu- <lcinin of the L)uti-li poot Francois Haversclimidt I'l-v-). PIETRA-DURA, pyfi'tra doo'ra (It., hard stone). A name given to the finest kinds of Florentine mosaic-work, in which the inlaid ma- teriiils are hard-stones, such as jasper, carnelian, amethyst, agate, etc. The real pietra-dura work dates as far back as the sixteenth century, about 1570: and from that time to the present has been almost confined to Florence, where a Government atelier has existed ever since the beginning of the seventeenth century. In the inferior kinds, which are sold in Italy, anil are also manufac- tured in Derbyshire and other parts of Britain, pieces of colored sea-shells are used instead of the harder and more valuable colored stones. PIETB.APERZIA, pya'trfl-per'tsd-A. A town in the Province of Caltanissetta, Sicily, seven miles southeast of Caltanissetta. It has an old Norman fortress, and carries on a trade in grain and almonds. There are sulphur and gypsum mines in the vicinity. Population (commune), in 1881. 11.284; in I'OOI. 12,826. PIETEASANTA, pya'tra-siin'ta. A town in the Province of Lucca. Italy. 15 miles northwest of Lucca by rail, and two miles from the Mediter- ranean. It is situated on a hill, on the top of which is a large fortress, and is surrounded by a wall. The fourteenth-century Church of San Martino has fine choir stalls and a baptistery with bronze decorations by Donatello. The sur- rounding country is fertile, and the grape and olive are produced in abundance. There are marble quarries and quicksilver mines. Popula- tion (CO lune), in 1881. 14.;582; in 1901, 17.444. PIETSCHMANN, pech'man. RiciiAim (1851 — ). A German Orientalist. He was born at Stettin, studied in Berlin and Leipzig, and in 1888 became university librarian at (ifittingen, where two years afterwards he received an ap- pointment to a chair of Kgyptology and Oriental history. He wrote; lUrmcx Trixmcfiislos ( 1875) ; (Jeschiclitc der Phoitizirr (1889); and transla- tions of Maspero's Oriental history (1877). and of the part dealing with Kgypt in Perrot and Chipicz, llistoirc dr I'nrt dans Vaniiquitf (1884). PIEZOMETER (from tik. vUieiv, piezein. to press + liirpov, i»c/ro», measure) . An instrument for measuring the compressibility of fluids. The name was given by Oersted (q.v.) to a piece of apparatus which he devised in 1822. and with which he was able to determine the compres- sibility of water, mercury, alcohol, and other liquids. It consisted of a cylinder of thick glass closed at either end by a brass cap. A tube of glass or brass containing a piston or a screw plug was fitted to the upper cap, by means of which considerable pressure could be e.xerted on the liquid in the cylinder below. This cylinder was suliiciently large to contain a glass flask whose neck was drawn out into a fine tube, like that of a thermometer, graduaterl into equal divisions, each of which represented a certain fraction of the volume of the llask. The flask was filled with the liquid whose compressibility was to be determined, and a small thread of mercury introduced into the fine tube. It was then placed inverted in the cylinder, which was filled with water, being so supported that the end of the fine tube dipped into a small vessel of mercury at the bottom. In this was placed another tube closed at its upper end, which acted as a manometer, enabling the observer to measure the pressure sustained by the liquid by the height of the mercurj- column. When the piston was pushed or screwed down, the liquid in the cylinder was put under pressure. This pressure was communicated to the liquid in the tlask. which was compressed by a small amount, as was shown by the use of the mercury in the fine tube. Knowing the volume of the flask and the value of the divisions of the tube, the amount of compressil)ility was readily ascer- tained by the pressure shown by the manometer, and in this way Oersted found that the com- pressibility of water for one atmosphere of pressure amounted to 40.05 millionths. Colladon and Sturm, who performed a series of similar experiments, made this value 49.05 millionths, while Grassi somewhat later fixed the com- pressibility of water at 0° centigrade at 50 millionths. and at S.*?" centigrade at 44 mil- lionths. With the piezometer it was also demon- strated that li((uids are perfectlj- elastic, since when the pressure is removed the mercury sinks to its former position, showing that the liquid returns to its original volume. PIFFERARI, piffa-ra're (It., pipers). The name given to shepherds of the Abruzzi who formerly flocked to Rome in the Advent season and collected gifts at the shrines of the Virgin, where they sang and played old airs on pipes and bagpipes. The pifTerari were among the picturesque features of Rome and usually went in
