MUSSOORIE-DEHRA DUN EPICENTRAL TRACT. gi 



15 minutes, they will not be considered further here. A report by- 

 Captain R. H, R. Thomas, R.E., of the times as registered on the 

 magnetograph curves at Dehra Dun, Kodaikanal, Barrackpore, and 

 Toungoo will be found at p. 292. 



Although the connection between the two events is not obvious, 

 Magnetic disturb- ^ * s ^cresting to note that a strong magnetic dis- 

 ance previous to turbance commenced at 6 a.m. on April 1st, and 

 quake * lasted until 4 a.m. on the 2nd. These disturbances 



usually coincide with the appearance of sun-spots, but in this case none 

 was visible. 1 Previous to the quake sun-spots had been last recorded 

 on the 2nd of March. The magnetic disturbance of April 1st and 2nd 

 was fully equal to the average disturbance recorded during the passage 



of sun-spots. 



Earthquake Forms — Dehra Dun. 



[Note. — As Mr. R. R. Simpson's special report on damage to 

 buildings in this town has just been given, the summary of the earth- 

 quake forms which follows only reproduces remarks referring to such 

 when they are of special interest. As the question of the time 

 of the main shock has also been gone into exhaustively by the Trigono- 

 metrical Survey officers for Dehra Dun' itself, it is also useless repro- 

 ducing a large number of mere guesses. Personal impressions of the 

 shock are given in some detail as their place could not be supplied by 

 later investigation. Aftershocks are all grouped together in a separate 

 chapter of this volume. As already explained in the Introduction, 

 it has been found impossible to quote every one owing to evidence 

 repeating itself and to lack of space. All sleepers were awakened.] 



Ram Ratan, Overseer, P. W. D. — The motion was like a machine sieve worked 

 by an engine. Bottles, clocks, etc., on shelves facing W. or E. fell. Buildings of 

 Indian Cadet Corps under construction (without roofs) suffered more than those 

 with roof complete. Hanging lamps swung roughly E.— W. 



Col. G. Strahan, R.E. — The first shock was violent and lasted about 50 sees, 

 in violent phase. (N.B. — The writer has had great experience in time measure- 

 ments in astronomical observations and thinks 50 sees, correct.) Chimneys were 

 thrown clear one to the N. 8° E. and one to S. S° W. The water of many tanks 

 washed over the N. side. Hanging lamp swung through 15° of arc in all direc- 



1 Solar photographs are taken twice daily at the Survey of India Offices.- 



