Believing that it is one of the functions of the purely scientific man to direct engineering attention to practical possibilities that will be of use in solving important problems, the author outlines the history of the photographic recording apparatus he describes later in detail and comments upon its general features that are of advantage in engineering practice, with illustrations, inclusive of the use that is made of the string galvanometer.
The subject of indicators for high-speed engines is discussed in general terms introductory to a full and detailed description of how this automatic photographic recording apparatus can be used to overcome difficulties that pertain to ordinary indicator-diagrams taken on the internal-combustion engine by former methods. A further use of this apparatus is in anti-knock research and its recent usage for this purpose is described and illustrated.
