s, the conical cross-tubes and angle rings.

Another aspect of the work of these departments is the immense
proportions of the modern machine tools used. This development is due
in great degree to the substitution of steel for iron. The steel
shell-plates of the largest boilers are 1-1/2 in. thick, and these
have to be bent into cylindrical forms. In the old days of iron
boilers the capacity of rolls never exceeded about 3/4 in. plate.
Often, alternatively to rolling, these thick plates are bent by
squeezing them in successive sections between huge blocks operated by
hydraulic pressure acting on toggle levers. And other machines besides
the rolls are made more massive than formerly to deal with the immense
plates of modern marine boilers.

The boiler and plating shops have been affected by the general
tendency to specialize manufactures. Firms have fallen into the
practice of restricting their range of product, with increase in
volume. The time has gone past when a single shop could turn out
several classes of boilers, and undertake any bridge and girder work
as well. One reason is to be found in the diminution of hand work and
the growth of the machine tool. Almost every distinct operation on
every section of a boiler or bridge may now be accomplished by one of
several highly specialized machines. Repetitive operations are
provided for thus, and by a system of templeting. If twenty or fifty
similar boilers are made in a year, each plate, hole, flange or stay
will be exactly like every similar one in the set. Dimensions of
plates will be marked from a sample or templet plate, and holes will
be marked similarly; or in many cases they are not marked at all, but
pitched and drilled at once by self-acting mechanism embodied in
drilling machines specially designed for one set of operations on one
kind of plate. Hundreds of bracing bars for bridges and girders will
be cut off all alike, and drilled or punched from a templet bar, so
that they are ready to take their place in bridge or girder without
any adjustments or fitting. (J. G. H.)

BOILING TO DEATH, a punishment once common both in England and on the
continent. The only extant legislative notice of it in England occurs in
an act passed in 1531 during the reign of Henry VIII., providing that
convicted poisoners should be boiled to death; it is, however,
frequently mentioned earlier as a punishment