4X0 Correspondence. [June, 
lasts, — i.e ., the time it lasts in each structural element is mea- 
sured by the time-interval between the beginning of the initial 
and the beginning of the terminal phase of the variation. 
Dr. Burdon-Sanderson has also submitted to the Royal Society 
an instrument for investigating the successive phases of the 
eleCtrical change which takes place in the excitable parts of 
plants and animals in consequence of excitation. 
Dr. Theobald Fischer considers that the climate of North 
Africa might be better amended by the planting of forests than 
by the proposed inland sea. 
General D. Ruggles, of Virginia, has taken out a patent for 
the artificial production of rain. It need scarcely be said that 
in England a process for the prevention of rain and the dispersal 
of clouds would be very much more useful. 
Prof. J. Milne, F.G.S., of the Japanese Imperial College of 
Engineering, in an article in the “ Geological Magazine,” shows 
that volcanoes are chiefly distributed along the borders of land 
which slopes steeply beneath the sea, and gives reasons why this 
should be the case. 
According to the comparative observations made by M. Alluard 
at Clermont and on the Puy-de-Dome during the past winter, 
the general rule may be deduced that whenever a zone of high 
pressures covers Central Europe, and especially France, there 
is, in our climate, an interversion of the temperature with the 
altitude, the cold being greater in the low grounds than on the 
heights. . 
[In the terrible frost of the early morning of Chnstmas-day, 
i860, the same phenomenon was observed in various localities 
in England. We learn that at Ainley Top, near Halifax, a lofty 
and generally cold situation, the thermometer stood 4 0 F. higher 
than at Elland in the valley below.— Ed. J. S.] 
M. Inostranzeff describes a mineral carbon, from the banks of 
Lake Orega, much harder than anthracite, which it also sur- 
passes in eledtric conductivity. If we arrange the forms of coal 
in the following series, lignite, bituminous coal, and anthracite, 
the new mineral follows after anthracite, and is still more di- 
vested of all organic charaaer. It is not readily combustible. 
Mr. Searles V. Wood, in the “ Geological Magazine,” asks 
how the glaciation of North America, as compared with that of 
Europe, is to be explained on Dr. Croll’s well-known eccentricity 
theory ? The superiority of temperature in Western Europe as 
compared with Eastern America, in corresponding latitudes, is 
generally admitted to be due to the existing oceanic currents. 
How, then, could a similar relation of temperatures prevail when 
these warm currents were supposed to be completely diverted 
from the glaciated ocean ? 
