ions are done by hand, but it is very interesting
to see self-working machines planing the sheets of metal to precisely
the required thinness with mathematical exactness. A pointed tool is
set to a certain pitch, and the plate of metal is made to revolve
in such a way that one continuous curl shaving falls until the whole
surface (back) has been planed perfectly true. The wood blocks are
treated in the same way, after being sawn into the required sizes by a
number of circular saws. Another set of workmen fit and join the metal
to the wood, trim the edges, and turn the blocks out type-high and
ready for working on the printing press.

A WET BLACKLEADING PROCESS.

In Messrs. Harper's establishment in New York, an improved wet process
of blackleading is adopted. The wax mould is laid face upward on the
floor of an inclosed box, and a torrent of finely pulverized graphite
suspended in water is poured upon it by means of a rotary pump, a
hose, and a distributing nozzle which dashes the liquid equally over
the whole surface of the mould. Superfluous graphite is then removed
by copious washing, an extremely fine film of graphite adhering to the
wax. This answers a triple purpose; it coats the mould with graphite,
wets it ready for the bath, and expels air bubbles from the letters.
This process prevents entirely the circulation of blacklead in the
air, which has heretofore been so objectionable in the process of
electrotyping.

A NEW FOREIGN PROCESS.

The galvanoplastic process of M. Coblence for obtaining electrotypes
of wood-engravings is as follows: A frame is laid upon a marble block,
and then covered with a solution of wax, colophane, and turpentine.
This mixture on the frame, after cooling, becomes hard, and presents a
smooth, even surface. An engraved wooden block is then placed upon the
surface of the frame, and subjected to a strong pressure. The imprint
on matrix in cameo, having been coated with graphite, is then placed
vertically in a galvanoplastic bath, and a cast, an exact reproduction
of the wood-engraving, is obtained. The shell is then backed with type
metal and finished in the usual way.--_Printer and Stationer._

* * * * *

A NEW SEISMOGRAPH.

All the seismographs that have hitherto been employed have two grave
disadvantages: they are either too simple, so that their indications
are valueless, or too complicated, so that their high cost and
delicacy, and th