hat part of the mountain which has been proved, after
the experience of many years, to be the least exposed to the
eruptions. The work is to be commenced immediately, and it is believed
that it will come into use during the present year. A sufficient
number of carriages are being built to convey 600 persons during the
day. The line is to be constructed upon an iron bridge, built after a
patented system.

* * * * *

THE POTTERY TREE.

Among the various economic products of the vegetable kingdom,
scarcely any hold a more important place than barks, whether for
medicinal, manufacturing, or other purposes. The structure and
formation of all barks are essentially very similar, being composed of
cellular and fibrous tissue. The cell contents of these tissues,
however, vary much in different plants; and, for this reason, we have
fibrous or soft, woody, hard, and even stony barks. To explain
everything which relates to the structure of bark would lead us into
long details which our space will not permit. Briefly stated, the bark
of trees (considering, now, those of our own climate) consists of
three layers. The outermost, called the "cortical," is formed of
cellular tissue, and differs widely in consistency in different
species; thus, in the cork oak, which furnishes man with one of his
most useful commercial products, the cortical layer acquires
extraordinary thickness. The middle layer, called the "cellular" or
"green bark," is a cellular mass of a very different nature. The cells
of which it is composed are polyhedral, thicker, and more loosely
joined, and filled with sap and chlorophyl. The inner layer (next the
wood), called the "liber," consists of fibers more or less long and
tenacious. It is from the liber that our most valuable commercial
fibers are obtained. In some plants the fibrous system prevails
throughout the inner bark; but what we wish to refer to more
particularly at present is a remarkable example of the harder and more
silicious barks, and which is to be found in the "Pottery Tree" of
Para. This tree, known to the Spaniards as _El Caouta_, to the French
as _Bois de Fer_, to the Brazilians as _Caraipe_, is the _Moquilea
utilis_ of botanists, and belongs to the natural order _Ternstroeiaceae_.
It is very large, straight, and slender, reaching a height of 100 feet
before branching; its diameter is from 12 to 15 inches; and its wood
is exceedingly hard from containing