riments with _simple_ and _inexpensive_ apparatus, such as, in a
majority of cases, is in his power to construct with the aid of
directions given in the book. The experiments given are rather of the
nature of _questions_ than of illustrations, and _precede_ the
statements of principles and laws. Definitions and laws are not given
until the pupil has acquired a knowledge of his subject sufficient to
enable him to construct them for himself. The aim of the book is to
lead the pupil _to observe and to think_.

C. F. EMERSON, _Prof. of Physics, Dartmouth College_: It takes up the
subject on the right plan, and presents it in a clear, yet scientific,
way.

WM. NOETLING, _Prof. of Rhetoric, Theory and Practice of Teaching,
State Normal School, Bloomsburg, Pa._: Every page of the book shows
that the author is a _real_ teacher and that he knows how to make
pupils think. I know of no other work on the subject of which this
treats that I can so unreservedly recommend to all wide-awake teachers
as this.

B. F. WRIGHT, _Supt. of Public Schools, St. Paul, Minn._: I like it
better than any text-book on physics I have seen.

O. H. ROBERTS, _Prin. of High School, San Jose, Cal._: Gage's Physics
is giving great satisfaction.

_Introduction to Physical Science._

By A. P. GAGE, Instructor in Physics in the English High School,
Boston, Mass., and Author of _Elements of Physics_, etc. 12mo.
Cloth. viii + 353 pages. With a chart of colors and spectra. Mailing
Price, $1.10; for introduction, $1.00; allowance for an old book in
exchange, 30 cents.

The great and constantly increasing popularity of Gage's _Elements of
Physics_ has created a demand for an equally good but easier book, on
the same plan, suitable for schools that can give but a limited time
to the study. The _Introduction to Physical Science_ has been prepared
to supply this demand.

ACCURACY is the prime requisite in scientific text-books. A false
statement is not less false because it is plausible, nor an
inconclusive experiment more satisfactory because it is diverting. In
books of entertainment, such things may be permissible; but in a
text-book, the first essentials are correctness and accuracy. It is
believed that the _Introduction_ will stand the closest expert
scrutiny. Especial care has been taken to restrict the use of
scientific terms, such as _force_, _energy_, _power_, etc., to their
proper significations. Terms like _sound_, _light_, _color_,