51 
Pacinotti, Gramme, Siemens, Alteneck and Lontin in some one of their 
modifications hold the field. Great progress has been made in the last 
fifteen years. Machines have assumed enormous proportions, and the 
number of branches of industry to which they have been applied is now 
very large. Much has been learned during this time, particularly with 
regard to alternating currents and their application to the transmission 
of power, the introduction of multiphase systems being of considerable 
importance in this connection. In the direction of high potential and 
great frequency the work of EB. Thomson and of Tesla is of great interest. 
Of the application of electricity to the production of light and heat little 
need be said in this connection. The difficulties to be overcome were 
largely mechanical, and with the progress made we are all familiar. As 
regards primary batteries there has been, of course, as we all know, con- 
siderable progress since the time of Volta. The number of forms brought 
into use has been enormous, and they have been important in increasing 
our knowledge of the relative electro-motive force of various combinations 
‘and in their bearing on chemical knowledge. It can hardly be said that 
an ideal primary battery has yet been obtained when we look at the sub- 
ject from a commercial point of view. Although the subject is not very 
much to the front at present, however, it is destined to come again, and 
I have no doubt it will be in a comparatively short time one of our lead- 
ing industries. The work of Planté and of Faure and others on sec- 
ondary batteries has been of great value commercially. They gave rise 
to several chemical problems, but the main difficulty here also has been 
of a mechanical kind, and they have not added much to the knowledge of 
electrical laws. 
The transformation of alternating current from high to low potential, 
and vice versa, by means of what are commonly called transformers, has 
shown another remarkable development of Faraday’s discovery of induced 
currents. The application of transformers has made it possible to dis- 
tribute electrical energy over large areas in a moderately economical 
manner and incidentally has led to considerable ‘increase in the knowledge 
of the magnetic properties of iron. One of the most important of the ap- 
plications of electricity is that of electro-chemistry. The chemical action 
of the electric spark was noticed by Von Groest and Dieman in 1739 in 
the decomposition of water. Becarri, about the middle of the eighteenth 
century, obtained metals from oxides through which the spark had passed, 
and in 1778 Priestley noted the production of an acid gas when the 
