408 BK. Emerson on Seebach’s Earthquake in Germany. 
rate map these towns were united by a straight line, and a Maca 
each other near the village of Amt-Gehren (lat. 50° 38-6’ N.; 
long. 8° 41-25’ E. of Paris) and fix the place of the epicentrum. 
In order to establish this more firmly, the author proceeds to 
discuss the remaining observations, and to construct isoseistic 
each minute up to the limit, Breslau, 4h. 5m. 25s., are deter- 
mined (plate 11), each curve when fully established uniting 
three or more places which reported the same time, and all 
having a common center at Amt-Gehren. As a result of the 
observations which deserve any confidence, above 40 per cent 
point directly to the same spot, a degree of accuracy far greater 
than could have been expected. 
For the determination of the true transit velocity, the depth 
abscissas (miles) measured off by the curve in passing over one 
unit on the axis of ordinates (minutes). For the earthquake 
under discussion this equalled 24 nautical miles per minute, or 
742 meters per second. The center of the hyperbola, or the point 
at which the asymptote prolonged cuts the axis of ordinates, 
- gives t°, i. e., the time of the initial shock at the centrum, and 
