302 MIDDLEMEN : KAXORA EARTHQUAKE. 



Compared with that of the co-seismal lines our knowledge of the 

 isoseismal lines (or curves of equal intensity) is suffi- 



Isosoismnl linrs. 



ciently complete, at least in the more central areas, 

 for them to be mapped in fair detail . This is so because of the less 

 evanescent character of the evidence as expressed in the ruined towns, 

 and because the principal areas in question were examined by the 

 Geological Survey. 



One of the special tasks undertaken by the officers' of that depart- 

 ment was this mapping of the areas of varying inten- 

 sity in accordance with a standard intensity scale. 

 The scale originally adopted was the Rossi-Forel, which is detailed 

 below — 



Rossi-Forel Intensity Scale. 



(I) Recorded by a single seismograph, or by some seismographs of 

 the same pattern, but not by several seismographs of different 

 kinds ; the shock felt by an experienced observer. [This 

 number of the scale is now obsolete owing to improvements 

 in seismographs.] 

 (II) Recorded by seismographs of different kinds ; felt by a small 

 number of persons at rest. 



(III) Felt by several persons at rest ; strong enough for the duration 

 or the direction to be appreciable. 



(IV) Felt by persons in motion ; disturbance of movable objects, 

 doors, windows ; cracking of ceilings. 



(V) Felt generally by every one ; disturbance of furniture and 



beds ; ringing of some bells. 

 (VI) General awaking of those asleep ; general ringing of bells ; 

 oscillation of chandeliers, stopping of clocks ; visible disturb- 

 ance of trees and shrubs. Some startled persons leave their 

 dwellings. 

 (VII) Overthrow of movable objects, fall of plaster, ringing of 

 church bells, general panic, without damage to buildings. 

 [Owing to poor material and construction in India damage to 

 buildings is considered to begin here.] 



