The thermal measurement of energy. Lectures delivered at the Philosophical Hall, Leeds

Preface

rjlHE following Lectures were delivered in Leeds, during the Spring of this year, at the request of the Technical Instruction Committee of the West Riding County Council.

At the close of the course I received, from those who had attended it, a request that the lectures should be published ; this request was subsequently repeated in a letter from the Secretary of the Technical Committee. I therefore now give the lectures (with a few trifling exceptions) in the form in which they were delivered.

It did not appear possible in such a course, and if possible I should not have considered it advisable, to enter on any detailed criticism of all the various determinations of the heat equivalent; suffice it to say, the selection of examples was in no sense arbitrary.

Some reference to the educational aspects of the subject are, I hope, justified by the fact that the greater portion of my hearers were teachers of science.

It is natural that an audience should criticise its lecturer ; but the reversal of the process may appear to vi Preface

be almost an impertinence. Nevertheless, I will venture to record some of the impressions I received during ray visits to Yorkshire. Informal classes were held at the close of each lecture, and from the experience thus gained, as Avell as from a study of the large number of letters forwarded to me during the course, I was in some degree able to appreciate the keenness and ability which were the characteristics of those with whom it was my good fortune thus to come into contact.

The reflection that hundreds of such teachers should have been willing to sacrifice their Saturday afternoons to the study of certain physical measurements which did not even possess the charm of novelty, may somewhat lighten the gloomy prospect sketched for us by those who hold pessimistic views as to the future of Intermediate Scientific Education in this country.

I take this opportunity of thanking Mr F. H. Neville and Mr W. C. D. Whetham, not only for their assistance in the revision of the proof-sheets, but also for many valuable suggestions and criticisms.

E. H. GRIFFITHS.

Sidney Sussex College, Cambridge,