METEOllOLOGY. 



CIRCULAR RELATIVE TO EARTHQUAKES. 



Sir : The Smithsonian Institution is desirous of collecting informa- 

 tion in reference to all phenomena having a hearing on the physical 

 geography of this continent ; and, in behalf of the Board of Regents, 

 it is respectfully requested that you will furnish us with any informa- 

 tion which you may possess, or be able to obtain, in regard to the 

 earthquake which lately occurred in your neighborhood. 



It will be interesting to determine the geographical limits of the 

 disturbance, and to ascertain whether it was confined to any particular 

 geological formation. If the direction of the shock was observed at 

 a few places, the centre of commotion could be determined ; and if 

 the time were accurately know n at different points, the velocity of the 

 earth-wave could be calculated, Hence^ an answer is requested to the 

 following questions, ^viz: 



1. Was the agitation felt by yourself, or by any other person in 

 your vicinity ? 



2. What was the approximate time of the occurrence ? 



3. What was the number^ and duration, of the shocks? 



4. What was the direction of the motion ? 



5. What was the character of the disturbance ? was it vertical, hori- 

 zontal, or oblique? was it an actual oscillation? an upheaval and 

 depression, or a mere tremor ? 



6. Was there any noise heard? and if so, what was its character? 



7. Was the place of observation on soft ground, or on a hard founda- 

 tion near the underlying rocks of the district ? 



8. Were any facts observed having apparently an immediate or 

 remote bearing on this phenomenon ? 



9.^ What v/as the intensity of the force in reference to producing 

 motion in bodies and cracks in walls ? 



Note. — Please reply to the first question, if to no other — for an 

 answer to it is necessary, in order to determine the limits of the com- 

 motion. 



The direction of the impulse may have been ascertained by ob- 

 serving the direction in which molasses, or any viscid liquid, was 

 thrown up against the side of a bowl. The remains of thejiquid on 

 the side of a vessel would indicate the direction some time after the 

 shock occurred. 



Yerj respectfully, your obedient servant, 



JOSEPH HENRY, _ 

 Becretary Smithsonian Institution. 



