viii
PREFACE
contained
were much longer delayed in publication, or, perhaps, were even lost to
science. Accordingly I informed Mrs. Lewis that if she would entrust
the manuscripts to me I would do my best to arrange them for
publication, ftating at the same time that I could not attempt more
than to act as an editor to the materials which had been left by her
late husband. From some of the documents it was obviously his
intention, had his life been spared, to have carried on his researches
and to have made additions to the original papers so as to bring the
subject down to the date of publication. But this task, as I told Mrs.
Lewis, I could not undertake. Parts of the subject lay rather ou'side
my usual lines of work, so that very much time would have had to be
spent in hunting through the geological, and more especially
mineralogical, literature of the last eight or nine years on the chance
of finding something throwing light on the questions treated by
Professor Lewis. As the hours which I can devote to prosecuting my own
investigations are none too numerous already, I was unable to undertake
what would have been of little profit and hardly any interest. To me no
work is so irksome as that of searching through periodicals on the
chance of lighting upon some contribution—possibly in itself of little
value—to the literature of a subject.
Thus
the two papers, forming the first and second sections of this book, are
printed very nearly as they were left by Professor Lewis. The
references have been tested and corrected, and a few changes have been
made here and there in phrase or in the order of sentences. These
changes, however, are merely editorial, such as the author himself
would have most probably made in finally revising his manuscript for
the press. Accordingly the statements printed and the results given
represent his views, at