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Tou eat ae een ean Rah neers 5 a ae Perey ey SS 
1886. | Recent Literature. 955 
thought by our author to be much below the truth, as there may 
be perhaps ten and perhaps one hundred, it being impossible to 
state the number definitely. 
Milne concludes, after a lengthy discussion of the facts, that the 
majority of earthquakes are due to explosive efforts at volcanic 
foci. “ The greater number of these explosions take place beneath 
the sea, and are probably due to the admission of water through 
fissures to the heated rocks beneath. A small number of earth- 
quakes originate at actual volcanoes. Some earthquakes are pro- 
duced by the sudden fracture of rocky strata or the production of 
faults. This may be attributable to stresses brought about by 
elevatory pressure. Lastly we have earthquakes due to the col- 
lapse of underground excavations.” 
The work concludes with brief chapters on earth tremors, earth 
pulsations and earth oscillations. 
WHEELER’s REPORT UPON THE THIRD INTERNATIONAL GEO- 
GRAPHICAL ConGress.—‘ Better late than never” is the adage 
ical congresses are held every five years, this volume just escapes 
being mistaken for a forecast of the fourth congress. Represent- 
atives from twenty-nine nationalities, embracing three-fourths of 
the earth’s inhabitants, were present. The question of a common 
initial meridian and uniform standard time seems to have been the 
Most prominent matter brought before the attention of the assem- 
bled geographers and explorers, but votes were taken upon forty- 
Seven questions. Among these were the exact trigonometrical 
determination of the position of light-houses, the establishment of 
subordinate meteorological stations to connect polar stations with 
those in middle latitudes; the desirability of registering the super- 
ficial temperature of the soil; the compilation of a universal pho- 
netic alphabet: the representation of mountains (in elementary 
atlases) by level curves; the fixation of a universal scheme of 
coloration for different heights, depths, and kinds of soil, and the 
Preparation of lists of the explorers of each country. The Ex- 
hibition was held in seventy-four rooms in the royal palace, and 
Was attended by about 150,000 visitors. 
e 
of the Government Land and Marine Surveys of the World, com- 
tion, functions, history, and progress of these surveys, with lists 
the general and special topographic maps published, etc. Capt. 
Wheeler states that in all the older civilized countries the topo- 
lic survey is the principal one, and that in all large and well 
or Organized Governments it has been continuously maintained under 
: Military administration. No such survey now exists in the United 
` 
