C. £. Dutton—Lifect of a warmer Climate upon Glaciers. 13 : 
going is applicable be rendered warmer then the position of 
zero must be taken at a lower point on Z, as at c, or what 
amounts to the same thing the curves must be drawn higher 
up relative to the zero line. Then the integral amount of cool- 
ing available for snow will be represented by the space below 
ec’ and within the two curves. It is evident that according to 
this construction the warmer climate would decrease the amount 
of cooling available for snow except in the case of one so cold 
that the temperature is always below zero—which may be rep- 
resented by drawing the zero line above both curves at aa’. 
(25.) But the same amount of cooling produces different 
amounts of precipitation in different parts of the temperature 
scale. While the amount of cooling available for snow has 
been diminished the efficiency of what remains has increased. 
In fig. 2, let Z, as before, be the axis for temperatures, and let 
Ss be the curve of saturation or maximum vapor density of 
water considered as a function of temperature. Let the vertical 
dimensions of the figures fand g represent equal amounts of 
cooling. Then their areas will exemplify the different amounts 
of precipitation in different parts of the temperature scale pro- 
duced by equal amounts of cooling. To combine the two fac- 
tors three axes are necessary. 
(26.) In fig. 8, draw the three rectangular codrdinate axes, 
OX, OY, OZ. Upon the plane YZ draw a convenient portion 
of the saturation curve Ss. Conceive the plane figure Sszz’ to 
be a generatrix moving along the axis OX in positions always 
parallel to ZY. The line zz’ will generate a vertical plane face, 
the line zs a horizontal plane face, and the line Ss a curved face 
of an indefinite solid. Conceive now two corrugated cutting 
edges similar to that of a sheet of corrugated iron and having 
the curvature generally expressed in fig. 1, by the curves PP’ 
and pp’ be passed into the indefinite solid, moving parallel to 
YZ, so as to cut out of it the shaded solid as drawn. This 
definite solid represents graphically the annual precipitation 
that precipitation takes place only when saturated air is coole 
The quantity of See et which cooling air will yield (per 
