of the bridge, and in a quarter of an hour later both ends rose from
their foundations. When the tide had risen 4 ft. the stage and bridge
were floated to the new position, when at 8.30 the girders dropped on
to their beds.

* * * * *




THE GENERATION OF STEAM, AND THE THERMODYNAMIC PROBLEMS
INVOLVED.[1]

[Footnote 1: Lecture delivered at the Institution of Civil
Engineers, session 1883-84. For the illustrations we are indebted
to the courtesy of Mr. J. Forrest, the secretary.]

By Mr. WILLIAM ANDERSON, M.I.C.E.


It will not be necessary to commence this lecture by explaining the
origin of fuel; it will be sufficient if I remind you that it is to
the action of the complex rays of the sun upon the foliage of plants
that we mainly owe our supply of combustibles. The tree trunks and
branches of our forests, as well as the subterranean deposits of coal
and naphtha, at one time formed portions of the atmosphere in the form
of carbonic acid gas; that gas was decomposed by the energy of the
solar rays, the carbon and the oxygen were placed in positions of
advantage with respect to each other--endowed with potential energy;
and it is my duty this evening to show how we can best make use of