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NEW YORK STATE MUSEUM 



great variety of mineral springs at that place, that west of Hoff- 

 man, near Johnstown, St Johnsville, Little Falls and elsewhere, 

 though of ancient date, are persistent lines of weakness along 

 which at any time further displacements may occur with their 

 attendant earthquake phenomena. 



It is a matter of scientific moment that such movements of the 

 crustal masses be recorded. Tradition and history have given us 

 accounts of severe and destructive earthquake shocks extending 

 along the Appalachian region, but the means of recording such 

 shocks whether of great or slender moment are at the present 

 time but partially adequate. In the entire Appalachian region 

 there are at present but two recording machines, one at Washing- 

 ton and the other at Baltimore. It has therefore seemed desirable 

 that the region of the more northern Adirondacks be covered by 

 the installation of a seismograph at Albany. 



The instrument which has been purchased for the State Museum 

 belongs to the type known as the horizontal pendulum. It is de- 

 signed to register all earthquake phenomena, whether violent or 

 mild in their manifestations, but it is specially adapted for record- 

 ing the feebler disturbances which commonly escape notice. It is 

 manufactured by Messrs J. & A. Bosch of Strassburg, and is 

 known as the Omori seismograph. 



The underlying mechanical principles on which this type of seis- 

 mograph is based were developed in Japan where the study of earth- 

 quakes in recent years has been undertaken on so wide a scale and 

 with such thoroughness that it leads all other countries in this line 

 of investigation. The same principles have been incorporated in 

 some of the other types of instrument now in use and have received 

 the approval of the best authorities. 



Briefly, the instrument consists of two parts, a pendulum and an 

 apparatus for registering the movements communicated to it, the 

 whole being mounted on a stone pier or similar foundation set in 

 the earth. 



The pendulum takes the form of a hollow rod supported at one 

 end against a conical standard by means of a pointed steel stud 

 that fits into a cup-shaped cavity on the rod. The penduhim car- 

 ries a massive lead weight at the other end and is held in a hori- 

 zontal position by two fine steel wires attached to a stirrup at the 

 top of the standard. The stirrup is fastened in turn to a carrier 

 which is provided with adjusting screws for raising or lowering the 

 weight. With this arrangement the pendulum, when in horizontal 

 position, can receive little motion from the supports, which is the 



