The subject of this excellent little book includes the Mechanical Properties of matter, and much that is usually treated under the head of Chemical Physics, such as Diffusion and Capillarity. It might be difficult to give a reason why electric and thermal conductivities of mercury, for example, should not be included among its properties as much as its density and its capillarity; but the distinction is convenient, and to some extent sanctioned by usage.

In the introductory chapters the author expounds some rather peculiar views with perhaps more insistence than is desirable in an elementary work. The word “force” is introduced apologetically, and with the explanation that, “as it does not denote either matter or energy, it is not a term for anything objective.” No one will dispute the immense importance of the property of conservation, but the author appears to me to press his view too far. As Dr Lodge has already pointed out, if conservation is to be the test of existence, Prof. Tait himself does not exist. I forbear from speculating what Dr Lodge will say when he reads on p. 11 that “not to have its price is conclusive against objectivity.”

Chapters IV. to VII. form an elementary treatise on Mechanics in which even the learned reader will find much that is interesting in the way of acute remark and illustration.