ear thee say in Roman key,
"_Paean! Ve-ni, Vi-di, Vi-ci._"

* * * * *

SALTPETRE AS A SOURCE OF POWER.

Every element of _strength_ in a civilized community demands special
notice. The present material progress of nations brings us every day in
contact with the application of power under various conditions, and the
most thoughtless person is to some extent influenced mentally by the
improvements, taking the places of older means and ways of adaptation,
in the arts of life.

We travel by the aid of steam-power, and we think and speak of a
locomotive or a steamboat as we once thought and spoke of a horse or
a man; and no little feeling of self-sufficiency is engendered by the
conclusion that this new source of power has been brought under control
and put to work in our day.

It is also true that we do not always entertain the most correct view of
what we term the new power of locomotive and steamboat; and as it may
aid us in some further steps connected with the subject of my remarks,
a familiar object, such as a steamboat, may be taken as illustrative of
the application of power, and we may thus obtain some simple ideas of
what power truly is, in Nature.

My travelled friend considers a steamboat as a ship propelled by wheels,
the shaft to which they are attached being moved by the machinery.
He follows back to the piston of the engine and finds the motor
there,--satisfied that he has discovered in the transference of
rectilinear to rotatory motion the reason for the progress of the boat.
A more inquisitive friend does not rest here, but assumes that the power
of the steam flowing through the machine sets in action its parts; and
he rests from farther pursuit of the power, where the larger number
of those who give any observation to the application of steam are
found,--gratified with the knowledge accumulated, and the readiness with
which an explanation of the motion of the boat can be traced to the
power of steam as its source.

We must proceed a little farther on our backward course from the point
where the power is applied, and in our analysis consider the steam as
only the vehicle or carrier of the power; and examining the conditions,
we find that water acted on by fire, while contained in a suitable
vessel, after some time takes up certain properties which enable it
to go forward and move the ponderous machinery of the boat. The water
evidently here derives its new chara