ON THE FACTS AND THEORY OF EARTHQUAKE PHENOMENA. 3° 
Occasionally also with reference to lunations. 
“With reference to sup- 
posed derivative or 
mean horizontal diree- 
tion of shock. 
With reference to direction, 
In space 4 .e. horizontal direction, of 
shock. 
And lastly, as to relative intensity, or dynamic value of the shock in each 
direction, which he arrives at on the assumption that this, in any given 
rhumb, is proportional to the xember of shocks observed in its direction in a 
given period, a supposition which—although perhaps not without some value, 
as admitting of one mode of regarding the relations of distant seismic regions 
not otherwise possible—admits of the gravest doubt whether it have any 
real natural basis. 
We shall consider the results in the order above. Near as Norway and 
Sweden are topographically to the British Islands, it is not with these, but 
with Iceland and the intervening band of the Northern Ocean that the 
Scandinavian peninsula is in connexion as a seismic region; very few ex- 
amples occur of simultaneous action between the former; but seldom has 
there been any marked convulsion in Iceland without commotion in Nor- 
way, &c., and vice versd. Scandinavia itself, one of the most remarkable 
masses of land in slow process of elevation in the world, also shows its con- 
nexion with internal action; and were it not that Iceland is pierced with 
numberless vents, broken and shattered in every direction by volcanic 
action, that admits of no cessation or consolidation above, there can be no 
doubt that the destructive power of earthquakes would be manifested in the 
northern peninsula to a far more serious extent and intensity. 
- That Greenland, at least the east coast, and the Farde Islands are shaken 
’ frequently, is highly probable, though I am not aware of any such record. 
: 
The following is the result of Perrey’s chronology of this region :— 
Tase I.—Harthquakes of Scandinavian Peninsula and Iceland. 
With dates of month or day. lor Season.|ycr, Total. 
Century a 8 | 5 : 
AD. |B) | Slel/Elelele| 4 
Sin 5 Alaei/elelealselelifisis g 
a/3 BIS)/Elsle| Si Sle} sl se | 3 
SIR |SId/SI5/65/4|n2(S|AZ/AlLE la 
KML to XVIL| 3) 2 i) a) 2}... |...) 0. fects. | fon ae ie fe 28 
|S a 1g o7. 9 5| (jan Nei tee) fea | aba bomen | 98) A | TE ews 3 Ven fe] pete BLE 
ee DALE Marti Fr Oe Bh Bl TO TON TT]: Gl 2. ] 113 
Wotals-.:3.:5..; 33] 20} 21) 13; 16} 10} 17) 13) 18} 17} 19) 17] 2] 4] 32) 252 
Winter |} Spring Summer | Autumn 
74 39 48 53 
ee ta OPS ge ith tows ovope to Depa eel papn ier 4 
“On examining this Table, Perrey remarks the same preponderance of 
earthquakes in the winter half of the year, that is evident from many of his 
other calculations for various regions. Here, for the six months of winter, 
there are 129 shocks, and but 91 for the summer half year. 
 Perrey is also of opinion, from the general result of his researches, that 
there is a preponderance of shocks at the equinoxes and summer solstice, 
which he denominates the “Critical Epochs” of the year. It is so for 
Scandinavia. 
B2 
