1889.] Geology and Paloeontology . 495 
made the subject of elaborate Reports by Dutch, German and 
English investigators.' 
These Reports have been recently published and have been 
ably reviewed in recent issues of the Contemporary and Edin- 
burgh Reviews. "" 
For a description of the physical characteristics of the great 
eruption the reader may consult these publications, but the 
scientific results as detailed in the several Reports may be 
briefly summarized. The process by which the eruption was 
brought about is considered to be typical of the phj^sical act- 
ion of volcanoes all over the world. Sea and surface water 
obtain access to the vent or to the heated rocks below it, and if 
brought suddenly into contact may give rise, by the develop- 
ment of steam, to earthquakes or eruptions of moderate strength, 
but it is to the slow percolation of water into rocks in a certain 
condition that the author of the English Report attributes the 
principal part in cataclysmal outbreaks. The water combines 
with the material of the rock, and by this combination the 
melting point of the rock is reduced ; it only requires the sub- 
jection of the hydrated compound to such heat as would be 
supplied by the anhydrous lavas in a fluid condition to disen- 
gage steam and other gases in enormous quanities, and 
to produce outbursts proportionate to the pressure and the 
strength of the inclosing walls. If, while this process is going 
on; water in large quanities gains access to the surface of the 
heated mass, solidification might take place and the escape of 
gases through the crater would be temporarily checked. When 
at last the accumulated force bursts the newly-formed crust, 
this and other obstacles would be speedily removed by the tre- 
mendous violence of the blast, and the sides of the crater 
might either be blown away or fall into the seething lava. 
Such appears to have been the working of the final eruption 
of Krakatoa. The objection that water could not percolate to 
great depths, owing to the upward pressure of steam, already 
^ Krakatau. Par. M. Berbeck. Public par ordre de Son Excellence le Gouver- 
neu^ General des Indes Nederlandaises. Batavia : 1884 and 1885. Paris : 1885 and 
appointed by the Royal Sockty" 1888. ^ "^ 
Untersuchungen uber Dammernngserscheir.ungen zur Erklarung der nach dem 
Krakatau-Ausbruch beobachteten atmospharisch-optischen Stornng. Von J. kiess- 
Img. Hamburg and Leipzig : 1888. 
» Contemporary Rn/iew, November, 1888. New York; Leonard Scott Publishing 
Edinburgh Review, January, 1889. New York ; Leonard Scott Publishing Co. 
