Show THE seismograph instrument WHICH 1 OP earthquakes every movement of abe earth Is ac curatelo cura tely recorded at washington office record of san francisco earthquake if science has not as yet discovered any method by which the coming of an earthquake can he foretold it ha perfected a delicate instrument which with the atmo t accuracy tells the story of the vibrations when they do occur this is the sets mcgraph and atie decord which it haa left of the re cat upheaval at san francisco has occupied the attention of scientists since then and drawn the ees of the general public to the in strument ment itself and people are asb ng what the aph is like and how it works it seems wonderful that an inspru ment located at washington could be able to record the earthquake at san francisco but such is the case in tact no vibration of earth surface any where on the globe however slight goes unnoticed oy this sensitive little earthquake up to the time of the upheaval which leveled the pa coast metropolis the delicate needle of the u mcgraph mo graph had beai tracing long sti light white lines on the of the record shet wednesday morning when it suddenly becala agitated at eight clock 19 amite and 20 seconds and began to make more or less elon gated waves at 8 25 clock the strong waves and the recording needle moved back and forth across the sheer then followed the most violent wives between 8 32 an I 1 8 35 bloc seventy fifth merl diar time as is shown by abe record at one time the antion of the needle was so vigorous thai its point went off the sheet which it kept in motion b a clock machin and the point did no return to the sheet until there was i secondary lull n the great disturb ance then when the needle had re fumed its tracings the earth bibra alons and waves until 12 35 when the agitation ceased each of the blaes on the record sheet represents an ho ir of time the move meat of the sheet keeping time with the tick of the connected clock tl e uni s of time are marked on thib sheet which is coverd with gelatine arc thus the observer is enabled to tell just when the eartha lakes began and when they end by the marl ing made by the nee lie point this instrument which is said to be one of the finest in the world was in stalled by prof A illis L moore ch ef of the united S cites weather b rea and Is un ler the dimmed ate control and supervision of the earthquake or seismographic iv ion of the b irea prof F marvici is head of this di cislon and sin e the san F alcisco li has shown ind described the instrument to many visitors it is installed in a basement La apartment THE seismograph away under the weather bureau build ing tar removed from the noisy hurly burly of the streets and is practical a mechanical recluse this instrument Is of a very su type and gives an accurate rec ord of the movement of the earth al the pendulum in the hon plane the mechanical principles involved in the construction of a seismograph of this type were first developed anc applied to the measurement of earth quakes in the latter part of 1880 by james A ewing then professor of me chanilal ch anical engineering at the university ot toldo but now professor of ism and applied mechanics at the uni versley of cambridge england nu berous modifications have since been incorporated in the instrument by gray and othera and in lt present form it Is well adapted tc measure and record all kinds of earth quakes except perhaps the most de ani Is especially suited to register the feeble unfelt earthquake which frequently occur in all parts ol 01 the world the instrument in the basement room of the weather bureau Is in stalled on separate castings secured to thick blocks of stone cemented firmly into the concrete floor of the building and projecting but a few inches aboe the floor level the foundation of the instrument is separate from the build ing being tar down in ane earth so that it will not be affected by art disturbances the extreme sensitiveness of the se is shown in the foil wing statement made by prof marvin rhe extreme sensitiveness to tilting is ex in several bays the weight of the observer almost anywhere on the floor of the small room in which the instrument is installed suffices to tilt the pendulum enough to show on the record a large displacement displace men is produced by standing at one side of the pedestal |