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: 
ON THE FACTS AND THEORY OF EARTHQUAKE PHENOMENA, 23 
they thus gave to science. I venture respectfully to commend it to our own, 
to the American, and to all European governments. 
- In his memoir on the Earthquakes of the United States and Canada, 
Perrey may be said to include the whole northern continent of America, 
with the exception of Mexico and Central America, to which he has de- 
voted another memoir. 
The two following tables, XV. and XVI., give the results of his discus- 
sion :— 
Taste XV.—Earthquakes of the United States and of Canada. 
Earthquakes with date of Day or Month. “ 
@ 
Century. | | | 8! . | 2 | 8 |S S| Tota. 
Ble | Qi e) 3) a) a i3 
Bo elas . ; os use Wes: |: 3 3 © 
= = al er | 2 (Sel) ane ie es = 8 a 
£|/2 a.|/ a] 8 Bole r= BS oS 2 
Ssilelsiqlel/Si4s4l4}/alol2azla 
BYiT....,;- rd eticw hk stl ch ioe ch ae Wah oe 4] 10 
XVIII Pocono a rea oll Oe On Ol) gata li le oo ps oe 
RIK. }:... Ae Ms rea fa ita) a (oro yl es! glee ln oe eb 
Total ...| 14] 14/12} 6{ 6| 4); 10] 14] 8/10) 19| 17 | 15] 149 
Winter Spring Summer Autumn 
40 16 32 46 
Here the number of earthquakes in autumn and winter are to those o! 
summer and spring as 88 to 49, or nearly as 2 to 1; and for Perrey’s critical 
periods :— 
SE Ct a i re a a9 
ppm POUANOR Ss as ce ns pes. oe oe es 18 
Smee SOMES Fn sp cise pepe pieniene LY 
Autumnal equinox ....... ssn Seems dG 
Perrey wholly disputes the verity of Humboldt’s conclusion (¢ Cosmos,’ t. i. 
p- 519, trad. p. M. Fays) that earthquakes are most frequent at the equi- 
noxes, and declares that the results of ail his memoirs prove the contrary. 
He discusses from his catalogue the relative number of shocks in each 
State of the Union; but this is comparatively of less importance to science 
than to social life. He has not been able to ascertain the northern limit of 
seismic action, but sees ground to believe it has reached Greenland more 
than once, but that frequent shocks pass no further north than the Canadas. 
The only records with direction of motion given are twelve in number, 
viz.,— 
PVA TOSS), lS ok POUR Pek ely UG 
Wee ROG goog), (IG au +8 
ee SW. . oho 4 PS 2 
Bias vere 22.12 Liss, ALOT Uel 2 1 
and calculating, upon his already known method, the mean direction from 
this narrow base, he finds it 
; N. 31° 54’ W., to S. 31° 54’ E.; 
but he confesses his own opinion, derived from a broad view of all the facts 
and the topographic character of the country, to be, that the prevailing 
direction is from north to south, or the contrary. 
