coils, i i, so as to deflect the needles, and that
the deflections of the needles follow, so to speak, the variations of
the currents. The electro-magnets are magnetized by a local battery;
permanent magnets might, however, take their place with a gain in
simplicity.

Now the writing pen, k, is connected to the nearest tip of the needle,
h, of each galvanoscope by threads, n n, which are kept taut by the
fibers, o_{1} o_{2} o_{3}, the springs, o, and the pins, o_{4}. In
this way the motions of the needles are recombined in the motion of
the duplicate pen upon the paper, p.

Fig. 1 is an elevation of the receiving instrument, in which i i are
the coils as before, j j j j the controlling electro-magnets, k is the
writing siphon dipping with its short leg into the ink well, m, and l
is the bridge from which the writing siphon is suspended by means of a
thread and spring. The long leg of the siphon reaches down to the
surface of the paper, p, which is pulled along beneath it in contact
with the film of ink filling the point of the tube. When the siphon is
at rest its point marks a zero line along the middle of the paper, but
when the receiver is working, the siphon point forms each letter of
the message upon the paper as it passes.--_Engineering._

* * * * *

ALUMINUM.

The splendid exhibit of the French aluminum manufacturers at the late
Exhibition has again called attention to that metal, which is so
admirably adapted to many purposes on account of its great lightness
and its stability under the influence of the atmosphere. While
aluminum industry has heretofore been thought to be confined to France
solely, we are now told by Mr. C. Bambery, in the Annual Report of the
Society of Berlin Instrument Makers, that for some years past aluminum
has been extensively manufactured in Berlin.

Three firms especially (Stueckradt, Haecke, and Schultze) are engaged in
this branch of industry.

The articles manufactured principally are nautical instruments, as
sextants, compasses, etc. The German navy is supplied throughout with
aluminum instruments. As a proof of the superiority of German
aluminum, it may here be mentioned that the normal sets of weights and
balances used by the International Commission for the regulation of
weights and measures, which lately was in session at Paris, were
obtained from Stueckradt, in Berlin, and not from any of the firms
at Paris, the reputed seat of al