i at Se 
ON THE FACTS AND THEORY OF EARTHQUAKE PHENOMENA. 9 
action in the winter reversed, so that shocks are more frequent in summer 
than in winter, and those in summer and spring together are to those in 
autumn and winter as 2 to 3, but the observed horizontal direction is dif- 
ferent, being most usual in the main line of the chain. 
If this be so, it would either be explicable as a case of deflected wave, like 
that already mentioned with regard to the general north and south line in 
Great Britain, becoming a south-west and north-east one in Scotland, the angle 
of deflection in the present instance being small; or it would indicate that 
some of the shocks of the Pyrenees have connexion with the Mediterranean 
seismic region. 
Spain, including Portugal, in its external configuration, with its vast 
table-land of the two Castiles, rising nearly 2000 feet above the sea, is 
perhaps the most interesting portion of Europe, not only in this respect, 
but as a region of earthquake disturbance, where the energy and destroying 
power of this agency have been more than once displayed upon the most 
tremendous scale. 
It may be worth while to place here the tables of the progression of the 
shocks of the two great Lisbon earthquakes of 1755 and 1761, as collected 
by Milne (Edinburgh Phil. Journ. vol. xxxi.) from various sources, 
although the chief result has been already discussed in the Second Report. 
The time given in the Tables is reduced to Lisbon time; the distances in 
degrees of seventy miles English each. 
Progressive rate of the shock, Lisbon earthquake of Ist November, 1755. 
Moment meee Time from 
Localities. observed : Font a impulse to |. Observations. 
of shock. | Presume arrival. 
origin. 
Presumed focus, lat. 30°) h m i ahd m 5 
PERLE Ws venseitessasanese 9 23 eee At sea. 
A ship at sea, in lat. 38°, 
Ronee OD Ag Wekecessscesc] 9 .-24 0 30 1 0 
PUBTERU ecu scsniessbaeienss see} 9 30 1 30 7 O | Portugal. 
MBRDOD ss csicescssevces gbusetraces 9 32 nod OTe G 
UE cacce yc <ds<ccenvex cess se 9 38 2 30 i "0 
POVAINIONGG, pescercssccoese nancac| fp et he a) 4 0 27 +O | Spain. 
MAEM Aiton custicesscaschescsscaces. 9 48 yee okt} 25 0 
Tangier and Tetuan ......... 9 46 5 30 23. 0 
Madrid...... Geet esccgienen coved 9 43 6 0 20 O 
MMMECA cease decsecsssacs esas 9 55 6 0 32) 30 
Funchal ..... Enesaaieseswasss 10 #1 8 30 38 0 | Madeira: 
IPGCESTNOULE. ps ssurcnccrvecscsers 10 3 12 30 40 0O 
BPRVT Ol acct ecccsccccascas Waie'ea sist 10 23 13,7710 60 0 
APHID OU cccesecdvebewasveccess: 10 27 13 30 64 0 
Yarmouth ......... Buansvccess 10 42 13ye0 79 #O [certain.) 
Eyam Edge.......+0... seaccoess 10 30 15 30 67 0 | Derbyshire (not 
MUPPET Sess coach eters essissss 9 58 17 «0 35 O | Uncertain. 
PIMSECPAAIN .sancdauasssmosscces LOG 1%.0 43 0 
BGEMOINGSS) .. veccasdesgubicags bese 10 42 18 0 oa OU 
Hamburgh ............ meaerses ll 43 20 0 | 140 O | Uncertain. 
Much uncertainty attends many of the statements as to time; and at 
several localities there is evidence that the shocks arrived much more 
rapidly than at others, in relation to distance. 
were felt at 92 33™, 
Thus at Cork two shocks 
The longitudes are from the meridian of Greenwich. 
