By Balfour Stewart, LL. D., F. R. S.

With an Appendix treating of the Vital and Mental Applications of the Doctrine.

I vol., 12mo. Cloth. Price, $1.50.

"The author has succeeded in presenting the facts in a clear and satisfactory manner, using simple language and copious illustration in the presentation of facts and principles, confining himself, however, to the physical aspect of the subject. In the Appendix the operation of the principles in the spheres of life and mind is supplied by the essays of Professors Le Conte and Bain." - Ohio Farmer.

" Prof. Stewart is one of the best known teachers in Owens College in Manchester.

"The volume of The International Scientific Series now before us is an excellent illustration of the true method of teaching, and will well compare with Prof. Tyndall's charming little book in the same series on ' Forms of Water," with illustrations enough to make clear, but not to conceal his thoughts, in a style simple and brief." - Christian Register, Boston.

"The writer has wonderful ability to compress much information into a few words. It is a rich treat to read such a book as this, when there is so much beauty and force combined with such simplicity. - Eastern Press.