the coin, and in modern coins the elevated ledge round the inscription,
that becomes first oxidated. In an English shilling of 1816 this ledge
exhibited a brilliant yellow tint before it appeared on any other part
of the coin.

If we use an uniform and homogeneous disc of silver that has never been
hammered or compressed, its surface will oxidate equally, provided all
its parts are equally heated. In the process of converting this disc
into a coin, the _sunk_ parts have obviously been _most compressed_
by the prominent parts of the die, and the _elevated_ parts _least
compressed_, the metal being in the latter left as it were in its
natural state. The raised letters and figures on a coin have therefore
less density than the other parts, and these parts oxiditate sooner or
at a lower temperature. When the letters of the legend are worn off by
friction, the parts immediately below them have also less density than
the surrounding metal, and the site as it were of the letters therefore
receive from heat a degree of oxidation, and a colour different from
that of the surrounding surface. Hence we obtain an explanation of the
revival of the invisible letters by oxidation.

* * * * *




THE GATHERER.

* * * * *

_Locomotive Engines_ have been established on the rail-roads near