REVIEWS. 
prominently mentioned in those works; and it is less new to scientific 
men, all of whom have long been familiar with the idea of forces being 
“modes of motion.” The phrase is not, however, repeated in other parts 
of the book. We consider that had the words, the modern philosophy of 
heat , or the modern philosophy of force as applied to heat, been substituted for 
the words “ a new philosophy,” the real facts of the case would have 
been more accurately described. The author has, however, in this 
excellent book, made this view of the nature of heat more popular and 
more demonstrable, by illustrating it with many beautiful experiments of 
his own and of other investigators, some of which are new ones. 
At page 2, the author says, “ For by mastering the laws and relations 
of heat, we make clear to our minds the interdependence of natural forces 
generally.” This statement, though perfectly true, and applicable to the 
science of heat, is equally time and applicable with regard to each of the 
physical forces ; and indeed it is correct of knowledge in general that a 
perfect acquaintance with any one branch discloses to us the inter- 
dependence of all branches of knowledge upon each other, and the general 
principles of that natural dependence and connection. 
The experiments of boiling water by heat of friction (page 10) ; of 
igniting a mixture of air and bi-sulphide of carbon by suddenly condensing 
it in a glass syringe (page 29) ; of melting fusible alloy by rotating it 
rapidly between the poles of a powerful electro-magnet (page 87) ; of the 
contraction of india-rubber by heat (page 88) ; and the rotation of metallic 
balls by means of a voltaic current (page 104) ; some of which appear to 
be of the author’s own devising, are carefully described and admirably 
illustrated. 
We were sorry to see (pages 128 to 181), under the headings “ General 
Laws of Professor Forbes,” and “ Laws tested experimentally,” the 
comparison again brought forward of the author’s more accurate con- 
clusions with the less accurate ones of Professor Forbes respecting the 
vibrations produced by the contact of bodies of different temperatures ; 
because having once shown (“ Philosophical Transactions of the Royal 
Society,” Part I., 1884) that the conclusions arrived at by Professor 
Forbes were incorrect, and having republished the paper in full in the 
‘‘Philosophical Magazine,” July, 1854, and again in the form of a lecture 
at the Royal Institution, Jan. 27, 1854, it appeared unnecessary to repeat 
the results in that form ; the accurate conclusions might have been 
described, and the refutation of Professor Forbes omitted. 
In Lecture VIII. (page 248) and its appendix (page 270), is a clear and 
full description of that most interesting experiment, the causing a fame 
of hydrogen burning in a glass tube to emit a musical sound, by pitching 
the voice to it at a distance in a proper note, and also causing that sound to 
cease by similar means. 
In various parts of his book the author largely employs mental imagery 
for the purpose of illustrating his views. lie speaks of the swinging of 
atoms (page 250) ; clashing of atoms (page 51) ; friction of atoms against 
pure space (page 33) ; the electric current knocking against the atoms, 
and imparting its motion to them (page 212) ; the passage of atoms from 
state of freedom to a state of bondage (page 153) ; the falling of atoms 
