Page:The New International Encyclopædia 1st ed. v. 17.djvu/840

* SEISIN. 762 SEISTAN. ueaniiig, the courts in some States using it as 8ynou,vuious with actual possession, 6nd otliers iu the sense of ownership. Consult: Blaekstone, Cummiiilariesj also 12 Law Quarterly Kcview, 241) (London, 1896). SEISMOGRAPH (from Gk. aeurfi.6s, scismos, cartluniaki' + ■yp(i(peii', gruphcin, to write), Seismomkter, or tSEisJioscorE. Names given to instruments designed tp indicate and record an eartlujuake shock. By the term seismoscope is generally implied an object that is moved by the earthquake and leaves a record of its motion. The .scisiiiomeler or seismograph, on the other hand, records tlie period, extent, and di- rection of the disturbance. A trough of mer- cury with notclics makes a useful seismoscope, as "the direction of the movement is indicated by noting the point where the mercury overllows. " Pendulums are also used as seismoscopes, and this form of apparatus has been rendered self- recording and forms seismometers or seismographs now in use. Thes(! pendulums consist of heavy masses delicately suspended so that they remain stationary during any vibration of the earth, and consequently can tracer a record of the move- ment of the earth willi respect to the pendulum. Two types of pendulum seismograph are used: those which eni])loy a vertical pendulum, such as the Italian observers have used for many years, and those provided with a horizontal pendulum, a form preferred b}' the Japanese, English, and European scientists. The horizontal pendulum was invented by Ilengler in 1832 and was subse- quently improved and adapted to scientific use by Professor Zollner of Leipzig. In connection with the horizontal pendulum a recording device is used which in the instruments constructed during the last few years is photographic and employs a moving strip of bromide or other paper on which a beam of light is reflected by mirrors connected with the apparatus. In former instru- ments a blackened surface on which a point traced a line and other registering devices were us^d. In the bracket arrangement of the hori- zontal pendulum a heavy weight is supported at the extremity of a horizontal bracket free to turn about a vertical axis at the opposite end. Any movement of the earth afl'ects the stand and surrounding objects, but is not communi- cated to the suspended mass. This instrument has been used in Japan in connection with a photographic register as described al)0ve. with considerable success. The horizontal pendulum of Professor Ernst von Rebeur Paschnitz of Merseburg is the form most used in Europe and has also been tested in Japan. In this apparatus there are one or two horizontal pendulums so that a vibration in any direction is recorded. A simple horizontal pendulum seismograph which is now extensively used was devised by Professor John Milne of" England. This instru- ment consists of a horizontal pendulum which carries a boom at whose extremity there is an s.luminum plate in which there is a transverse slit. This slit is placed above and at right angles to a second slit beneath which there is a moving band of bromide paper. Light from a lamp is reflected through the intersection of these two slits in the form of a point when the two slits are in their position of rest, and makes a straight line on the moving paper. If there is any movement of the earth there is a move- ment of one slit -with respect to the other, caus- ing a wnyj line to be produced which indicates the tremors observed at the particular station. A clockwork arrangement opens and closes a shutter at regular intervals so that the light from the lamp makes a record of the time on the moving strip. Professor Milne in his observa- tory on tlio Isle of Wight using such an instru- ment is able to detect disturbances in Japan, Borneo, South America, or elsewhere, and the seismograms thus obtained, taken in connection with telegraphic information and interchange of observations at other stations, enable the velocity, wave movement, source, and other features of an earthquake to be studied. .Record iCylinder OMORI SEISMOGRAPH OF U. 8. WEATHEIl BUHEAU. For further information on seismometers, the reader is referred to Milne, Earthquakes and Other Earth Movements (London and New York, 18S6) ; miscellaneous papers on seismology in Nature (London), by the same author; Reports of the Committee on Seisnio- logical Investigations of the British Associations (to be found in the annual reports of the meet- ings of the association) ; and The Seismological Journal u( Japan. See E.RTIIQUAKE. SEISMOLOGY. See Earthquake. SEISS, ses, Joseph Augustus (1823-1904). An American Lutheran clergyman. He was liorn at Graceham, Md., and studied for two j-ears at Pennsylvania College, Gettysburg. After a course of private instruction in theology, he became a pastor at Martinsburg and Shepherdstown, Va., in 184S, moved to Cumberland, then to Balti- more, Jld.. and in 1858 became pastor of Saint -John's, Philadelphia. In 1874 he built and in- augurated the Church of the Holy Communion in that city. For twelve years he was editor of The Lutheran and for a time an editor of The Prophetic Times; also a founder of the General Council of the Church. Some of his books are: Baptist Sustem. Examined (1854; 3d ed. 1882) ; Last Times (1856; 7th ed. 1880); Ecciesia Lu- therana (1867) ; Lectures on the Gospels (187S) ; Luther and the Reformatinn (1883). SEISTAN, sas-tan', or SISTAM". A region in Eastern Persia and Southwestern Afghanistan, be- tween latitudes 30° and 31° 35' N.. and longi- tudes 60° and 62° 40' E. (Map: Persia. H 5). The Persian-Afghan boundary was determined