n he has made, and it is
hardly to be hoped that he has in all--or even in the majority of
cases--succeeded in recommending absolutely the best method of
procedure.

This brings another point into view. Before all things the means
indicated must be definite and reliable. It is for this reason that
the writer has practically confined himself to matters lying within
his own immediate experience, and has never recommended any process
(with one or two minor exceptions, which he has noted) which he has
not actually and personally carried through to a successful issue.
This, although it is a matter which he considers of the highest
importance, and which is his only title to a hearing, has
unfortunately led to a very personal tone in the book.

With regard to the arts treated of in the following pages, matters
about which information is easily acquired--such as carpentering,
blacksmithing, turning, and the arts of the watchmaker--have been
left on one side. With regard to the last, which is of immense use in
the laboratory, there happen to be at least two excellent and handy
books, viz. Saunier's Watchmakers' Handbook, Tripplin, London, 1892;
and Britton's Watchmakers' Dictionary and Guide.

With regard to carpentering, turning, and blacksmithing, almost any
one who so desires can obtain a little practical experience in any
village. A short chapter has been devoted to glass-blowing, in spite
of there being an excellent and handy book by Mr. Shenstone (The
Methods of Glass-blowing, Rivington) on the subject already in
existence. The reason for this exception lies in the fact that the
writer's methods differ considerably from those advocated by Mr.
Shenstone.

The chapter on opticians' work has had to be compressed to an extent
which is undesirable in dealing with so complex and delicate an art,
but it is hoped that it will prove a sufficient introduction for
laboratory purposes. In this matter the writer is under great
obligations to his friend and assistant, Mr. James Cook, F.R.A.S, who
gave him his first lessons in lens-making some twenty years ago. To
Mr. John A. Brashear of Allegheny, Pa, thanks are due for much
miscellaneous information on optical work, which is included verbatim
in the text, some of it contained originally in printed papers, and
some most kindly communicated to the writer for the purpose of this
book. In particular, the writer would thank Mr. Brashear for his
generously accorded informatio