The paper deals with : -the first, cooling and contraction curves of rapidly and slowly cooled cast iron from melting to ordinary temperatures obtained by a special apparatus of the author's own design, and the results are discussed into some detail, formulating them finally in some mathematical expressions; the second, density and shrinkage of cast iron which occluded air while pouring is discussed from the results of experiments on high and low head castings which differently occluded air, and the conclusion therefrom is shown as such, porous or gas occluded cast iron of lower density shrinks more than less porous iron of higher density.

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This paper deseribes about the various results of experiments done on high speed diesel engine for driving dynamo at the testing shop of Ikegai Iron Works, Ltd. Firstly the authors describe about the general characteristics required as dynamo engines, which are as follows : -1. Constancy of speed. 2. Closespeed regulation. 3. Smooth running at any load. 4. Flexibility. Then they mention about the points which should be controlled automatically in case of air injection diesel engine, as follows : -1. Pressure of injection air. 2. Supply of fuel oil. 3. Lift and timing of injection valve. 4. Supply of compressed air. Then they draw attension that most of diesel engines in use are necessary to adjust the pulverizer properly according to the differnt quality of fuel oil in use. Now turning to the experiment of diesel engines herein described, they faced to many difficulties about the above mentioned points, as the engine itself was the type of special light construction following to the requirements of its customer. These points of difficulties and the method of remedies are described in details. The "Ikegai's" patent fuel injection valve which has been in use for some times usual type of engines have proved to be equally successful for special light type engine if it has been assisted by the special governing system which has been developed by them during the trials of the engine. This combination of patent injection valve and special governing system enabled its speed regulation into very close range, condition of running very smooth and steady and use of any grade of fuel oil without adjustment of pulverizer as other type of diesel engine require. As a few example of this close range of regulation, following figures may interest the readers : -a. With 3 cyl. 130 B.H.P. intermediate speed engine : -Instanteneous change of number of revolution per minute to be 3.6 to 3.1% when load was switched off from full load to nil. b. With 6 cyl. 200 B. H.P.high speed light type engine with extra light fly wheel : -Ditto : -7.1 to 5.7%.

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