Causes and Conditions of Glaciation. — Upham. 15 
Manson, a civil engineer of San Francisco, California. This 
ingenious and well argued hypothesis is published in volume 
vni of the Transactions of the Technical soeiet} T of the Pa- 
cific Coast (Sept., 1891), and separately, in a somewhat mod- 
ified and more extended form, in a pamphlet of 40 pages, 
"Geological and Solar Climates, their Causes and Variations" 
(Department of Geology and Physics, University of Califor- 
nia. May, 1898). Kendall reviews Mr. Manson's work as fol- 
lows in the February number of the Glacialists' Magazine: 
According to the author, during the earl} stages of cooling of the earl h 
water-vapor would be present in the atmosphere in such quantities as to 
quite shut out the heat rays, though not the light rays, of the sun: and 
therefore the effect oft lie solar rays would be limited to heating the outside 
of a cloud shell, and so retarding' the secular cooling of the earth. The 
cloud canopy would be effective in obstructing ingress as well as egress 
of heat rays. The isotherms would depend solely upon altitude and not 
at all upon latitude. As the earth slowly cooled, the isothermal shells 
would successively shrink down upon the surface. When the surface 
temperature was !>0° F.. "a particularly uniform, moist, and highly tor- 
rid climate was established culminating in the Carboniferous 
age.'" With further cooling, temperatures corresponding with tropical 
and then temperate climates would prevail the world over. The iso- 
therm of 32° F. would touch the mountain tops ami a snow-line would 
be produced. ••From the moment that snow began to accumulate. 
every remaining vestige of earth heat was available for producing those 
conditions favorable to glaciation. namely, warm seas, dense fogs, and 
<'old continental areas: and every unit of solar energy reaching the up- 
per regions of the atmosphere was available for maintaining those favor- 
able conditions. Glaciation under these conditions would be cumula- 
tive until the oceans, exhausted of their heat and lessened in area, 
were no longer able to supply the moisture necessary to completely 
shroud the earth from direct solar heat." 
The culmination of ih i' Ice age, according to the author, was made b\ 
the gradual reduction of the waters of the oceans to a temperature of 
31° F. down to the bottom, the present bottom temperature of the 
oceans, and the consequent reduction of evaporation permitted the sun's 
rays at last to break through, and to their heating power the disappear- 
ance of the ice-sheets is ascribed: but, just as the high specific heal of 
water kept the oceans warm long after glacial conditions had super- 
vened upon t he land, so now the same property retards their recoverj 
under the genial influence of the radiant heal of the sun. In the author's 
opinion the Climate of the whole earth is becoming warmer, and he ap- 
peals to the general retreal of glaciers in proof. 
Each of thes. • discussions doubtless presents, in greater or 
less degree, some useful portion or hint of the truth: but each 
