There are many causes, for the inducement of Casting-Stresses produced in the metal on account of it being cast. The subjects treated here may be said to belong to one of these causes and are considered to have vital connections with the stress inducements. With this in mind, the present investigation was performed as a part of the study of casting-stresses, which the author is now pursuing. With ordinary grey iron as was used in the present investigation, the results of shrinkage tests due to different pouring heads are : after the metal is poured in the moulds, it first expands and then contracts, and the high head casting expands more than the low head, but contracts less, provided sound castings be secured. The mean density of low head iron, as is usually imagined, is less than that of high head iron, varying by the difference of heads ; the higher head, the higher density, and vice versa. And also the density of the casting varies according to its distance from the pouring gate, regardless of the height of the head. The Apparatus designed by the author for measuring expansion and contraction of cast metal in the present study is explained in Appendix I., and the degree of accuracy in the determination of densities in Appendix II.
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