The plain truth is, boilers have of late become gigantic foes to
human life. Explosions have increased, are increasing, and should be
diminished; and they are, in many instances, caused by boilers being
strained and weakened by sudden contraction from having their surfaces
exposed when the fire has been withdrawn from them. Boilers are also
materially injured by the excessive furnace heat which it is necessary
to maintain to compensate for the large amount of caloric which
is dissipated from their surfaces, not only by radiation but from
absorption by the surrounding atmosphere.

As the views here laid down are drawn exclusively from the region of
fact and experiment, it is to be hoped that an enlightened sense of
self-interest may prompt those whom the subject may concern, to give it
that special attention which its importance demands.

* * * * *




Attachment of Saws to Swing-Frames.


To insure the efficiency of mill-saws, it is highly important to have
them firmly secured in the frames by which they are reciprocated.
Swing-frames for carrying saws are ordinarily of wrought iron or steel,
and made up of several pieces mortised and tenoned together in the form
of a rectangular frame or parallelogram, of which the longest sides are
termed verticals and the shortest crossheads or crossrails. In the case
of deal frames, the swing frame differs somewhat from that of a timber