The great and increasing importance of internal combustion motors is perhaps scarcely realized by the general public. For industrial purposes they have for many years been steadily gaining favour, and now hold an assured position. It is only in the last few years, however, that we have begun to recognize the drawbacks of horse-drawn vehicles, and the immense advantage gained by propelling them mechanically.

The suitability of oil engines for the purpose has awakened a widespread interest in them. The Editor therefore hopes that this little volume will be especially welcome to non-technical readers who like to keep ahead of the times in matters of such universal importance.

One chapter deals exclusively with the theory of the gas engine, but the non-technical mind should have no fear, for mathematics have been as far as possible avoided. It may also serve to dispel wrongful notions concerning the practical limits of the efficiency of gas engines which, we are sorry to say, exist even among persons living in a scientific atmosphere.

We have not spoken in the text of the extremely interesting results obtained from the oil engine invented by Herr Diesel of Berlin, because it has not yet been proved that this motor is strictly practicable. If, however, it turns out to be a commercial success, we hope to add a description of it at some future date.

May 1898.