Propagation of the Charleston Earthquake. 



11 



Locality. 



State. 



Distance. 



Time. 



W't. 



Remarks. 



Brooklyn. 



N. T. 



643 



54m 



30- 



3 



mean of 4 good obs. 



New York, 



N. Y. 



645 



54 



12 



6 



mean of 10 obs. 



Haokensack, 



N.J. 



654 



54 





L 





"Warwick. 



N. Y. 



661 



56 





1 





Go wan da, 



N. Y. 



666 



55 





1 





Detroit, 



Mich. 



675 



55 



12 



3 



mean of 5 obs. 



Valparaiso, 



Ind. 



705 



53 





1 





London, 



Ont. 



706 



55 





1 





Peoria, 



111. 



710 



55 





1 





New Haven, 



Conn. 



711 



55 



30 



2 



mean of 2 obs. 



Fort Huron, 



Mich. 



712 



55 





1 





Hudson, 



N. Y. 



747 



57 





1 





Hartford, 



Conn. 



747 



54' 



45 



2 



mean of 2 good obs. 



Stuyvesant, 



N. Y. 



760 



57 





1 





East Saginaw, 



Mich. 



766 



58 





1 





Albany, 



N. Y. 



770 



56 



40 



1 





Fonda, 



N. Y. 



775 



55 





1 





Saratoga. 



N. Y. 



797 



53 





1 





Greenfield, 



Mass. 



799 



55 





1 





Keokuk, 



Iowa. 



810 



56. 





2 



2 obs. 



Dighton, 



Mass. 



812 



56 





1 





Davenport, 



la. 



827 



55 





1 





Lake Placid, 



N. Y. 



827 



55 





1 





Jamaica Plain, 



Mass. 



82S 



57 





1 





Blue Mt. Lake, 



N. Y. 



830 



56 





1 





Bellows Falls, 



Vt. 



832 



53 





1 





Boston, 



Mass. 



832 



55 



30 



1 



2 obs. 



Dubuque, 



la. 



878 



57 





1 





Prairie du Chien, 



Wis. 



924 



56 



30 



1 





Taking these in 



groups 



in the manner ji 



cist indicated we ha\ 













Weig 



ht. Residuals. 



Centrum 



x -j- 



Oy = 









2 



+ 4-06 



to 155 



X + 



Illy = 



39 





9 



+ 1-90 



203 to 284 



X -j- 



240\/ = 



84 





8 



— '28 



302 to 377 



X + 



342y = 



122 





7 



- 4-43 



405 to 491 



x -j- 462?/ = 



158 





16 



— -60 



501 to 588 



x -i- 



542y = 



184 





18 



— -05 



608 to 675 



X -f- 



647y = 



217 





20 



+ 1-80 



705 to 799 



X -4- 



744 y = 



255 





15 



- 4-00 



810 to 924 



X -f- 



83 1y = 



278 





11 



+ 3-85 



The normal equations are : 



106a; 4- 55768?/ = 18940. 

 55768x + 34474772*/ = 11668675. 



The solution gives x = + 4-06 ± 1*7 seconds, y = 0*3319 ± 

 0-0029. The resulting speed is, 3-013 ± 0-027 miles or 4848 

 ± 43 metres per second. To this result some correction must 

 be applied for the systematic error, which, as already stated, 

 there is reason to believe probably lies between one-tenth and 

 one-twentieth of the mean time-interval and therefore of the 

 speed. Suppose it be taken at one-fifteenth of the amount, 

 with a probable error of one third of the correction. This 



