<div class="htmlview paragraph"><b>THIS paper points out that, with the solid-injection Diesel-engine, the reliable smooth-combustion performance of the old air-injection type has not been duplicated, especially so with the high-speed Diesel-engine.</b></div> <div class="htmlview paragraph"><b>To get the specific output as high as possible, and to obtain good fuel-economy, it is necessary to have the first part of the combustion approaching the constant-volume cycle, while the rest of the combustion is rather slow. In other words, the rate of burning is a maximum at the beginning and decreases toward the end of the combustion. The rate of burning in a gasoline engine is slow at the beginning and becomes a maximum at the end of the combustion, neglecting the slight after-burning.</b></div> <div class="htmlview paragraph"><b>Comparison is made between the rate of burning of different types of high-speed Diesel-engines and the rate of burning of the gasoline engine. It is shown that, besides the hydraulic mixing of fuel and air, an increased turbulence is required toward the end of the combustion to obtain an efficient rate of burning.</b></div> <div class="htmlview paragraph"><b>A desirable indicator-card is shown, the increase of the rate of burning being comparatively small and the rate of pressure-rise very moderate for the high specific output.</b></div> <div class="htmlview paragraph"><b>The Lanova engine is explained, in which the burning takes place with increasing rate for 80 per cent of the fuel burned as compared with the gasoline combustion in which 90 per cent of the fuel burns with increasing rate.</b></div>