ON THE FACTS AND THEORY OF EARTHQUAKE PHENOMENA, 43 
Quite recently, again, I felt the same painful surprise at reading the instruc- 
tions given to M. Raffenel. : 
“Does Abyssinia form an axis of convulsion perpendicular to the Arabic 
axis? or is it the eastern extremity of an unique axis formed by the great 
Ethiopic chain, and crossing the African continent at its greatest breadth ? 
“Jn nearly the same latitude as Abyssinia, but on the western coast of 
Africa, we find the sources of the Senegal and Gambia vividly coloured in 
M. Berghaus’s map. What evidence has the author for this statement? 
With respect to this region, I am only acquainted with the two following 
descriptions drawn from M. Walcknaér's collection.” We read, at t. vi. 
p- 181, “ The aspect of the mountains Nikolo and Bandeia prove that this 
country has been the theatre of volcanic eruptions. Earthquakes are very 
frequent; and shortly before M. Mollieu’s visit, one of the most violent had 
occurred, the shocks of which had been felt as far as Timbo.” And further 
on, p. 184, “ The mountains, covered with ferruginous stones and cinders, 
which enclose the valley in which are the sources of the Senegal and Gambia, 
lead M. Mollieu to believe that they occupy the crater of an extinct volcano. 
This traveller was at the source of the Gambia, April 8, 1818.” 
It is useful to compare this passage with the following, extracted from 
the same collection, t. xii. p. 356 :—“ There is no record in Senegal that 
any portion of the colony has ever experienced an earthquake.” 
Without seeking to justify the accuracy of M. Berghaus, it may not 
be uninteresting to remark that the Antilles and the Republic of Guate- 
mala lie under the same parallel of latitude (about 15° N.) as Abyssinia and 
the sources of the Gambia. 
Can there be an axis, or rather an immense zone, of convulsions parallel 
to the Equator? Often convulsed in the western counterforts (the Archi- 
pelagos of Cape Verd and the Canaries), Africa suffers also in the S.E., 
in the great southern chain of Madagascar. I find in M. Seguérel de la 
Combe that “earthquakes are very frequent in Madagascar. When they 
occur, the natives leave their houses and commence beating the walls with 
their hands. They do not allege any reason for this conduct but custom.” 
(‘ Voy. a Madagascar et aux Iles Comorres,’ t. i. p. 3.) 
Let me add this remark from an ancient traveller in Madagascar : “ Hap- 
pily earthquakes are here completely unknown.” (Le Gentil, ‘ Voy. dans 
les Mers de |’Inde,’ t. ii. p. 367.) 
If we subjoin to these contradictory statements the few facts which we 
possess, we shall justify M. Berghaus’s not having coloured the south of 
Africa. 
“1786, August 4, 6°35 A.m., in the Isle of France, two violent but harm- 
less shocks. ‘The motion was horizontal and vertical. The barometer was 
not affected. Earthquakes are of rare occurrence. The volcano in Bour- 
bon, active from the 5th of June previous, emitted much lava upon this day, 
but the island was not sensible of any shocks.” (Péron, ‘ Voy. aux Terres 
Australes,’ 2nd edit. t. i. p. 134; ‘ Ephémér. de Manheim,’ 1788, p- 397.) 
1809, 8th of January, the island of Penguin, close to the Cape of Good 
Hivpe, was swallowed up by an earthquake. Iam unacquainted with this 
island, and U only find this circumstance related in an anonymous work 
entitled ‘ Mémorial de Chronologie,’ t. ii. p. 932. 
Here, again, relative to another earthquake of the same year, 1809, are 
the details communicated by M. Barchers, Minister of Stellenbosch (country 
of the Hottentots), to Campbell (end of November 1812), concerning the 
first of the earthquakes which occurred three years previously :— 
“The church of Paarl was then vacant. The governor begged me to preach 
