The following may be stated as well proved:

1. That steel armor promises to replace both iron and compound.

2. That projectiles designed for the piercing of hard armor must be
made of steel.

3. That the larger the plate, the better it is able to absorb the
energy of impact without injury to itself.

4. That the backing must be as rigid as possible.

* * * * *

[FROM ENGINEERING.]




THE COMPRESSED AIR SYSTEM OF PARIS.


The demand for compressed air as a motive power is constantly
increasing in Paris; the company, according to its official reports,
is financially prosperous, and it seems difficult to understand how it
should continue as an actively going concern, unless it at all events
paid its way. The central station of St. Fargeau, originally started
on modest lines, for maintaining a uniform time by pneumatic pressure
throughout Paris, has grown rapidly to very large proportions, though
it has never been able to supply the demand made on it for power; and