only the end
kilns are braced in this way. The intermediate ones are supported below
by wooden braces, securely fastened at the bottom. The roof is always
arched, is one brick, or eight inches, thick, and is laid in headers,
fourteen being used in each superficial foot. Many of the kilns have in
the center a round hole, from sixteen to eighteen inches in diameter,
which is closed by a cast iron plate. It requires from 35 M. to 40 M.
brick for a kiln of 45 cords, and 60 M. to 65 M. for one of 90 cords.

* * * * *

The belief that population in the West Indies is stationary is so far
from accurate that, as Sir Anthony Musgrave points out, it is increasing
more rapidly than the population of the United Kingdom. The statistics
of population show an increase of 16 per cent. on the last decennial
period, while the increase in the United Kingdom in the ten years
preceding the last census was under 11 per cent. This increase appears
to be general, and is only slightly influenced by immigration. "The
population of the West Indies," adds Sir A. Musgrave, "is now greater
than that of any of the larger Australian colonies, and three times that
of New Zealand."

* * * * *

HEAT DEVELOPED IN FORGING.

M. Tresca has lately presented to the Academy of Sciences some very
interesting experiments on the development and distribution of heat
produced by a blow of the steam hammer in the process of forging. The
method used was as follows: The bar was carefully polished on both
sides, and this polished part covered with a thin layer of wax. It was
then placed on an anvil and struck by a monkey of known weight, P,
falling from a height, H. The faces of the monkey and anvil were exactly
alike, and care was taken that the whole work, T = PH, should be
expended upon the bar. A single blow was enough to melt the wax over a
certain zone; and this indicated clearly how much of the lateral faces
had been raised by the shock to the temperature of melting wax. The form
of this melted part could be made to differ considerably, but
approximated to that of an equilateral hyperbola. Let A be the area of
this zone, b the width of the bar, d the density, C the heat capacity,
and t-t0 the excess of temperature of melting wax over the temperature
of the air. Then, assuming that the area, A, is the base of a horizontal
prism, which is everywhere heated to the temperature, t, the heating