The authors, who already explained the technical contents of a part of the provisions of the Rules last year, now desire to explain on the Beam, Beam runner and Deck girder.

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The well known method of drawing the longitudinal strength curves-the shearing force curve and the bending moment curve-has been used heretofore without any basic improvement, inspite of its troublesome process. The authors propose here some fundamental modifications in the process, expecting to serve for saving time and labour to be spent in the work.

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In this paper the author deals with fatigue properties of Butt and Tee welded mild steel at room and elevated temperature, also he tried to determine what is the creep resistance at 450°C.
Finally he takes up practical aspects of the influence of time on the quench and edge-hardening.

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The authors experimented the riveted joint and concluded as follows;
I. The thickness of strap may be reduced.
II. For seam jo nt the sectional area of rivets shall be smaller than that of plate at the centre line in a row of rivets.

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Manganese bronze, which, in order to obtain merely a high tensile strength, being structurally become all β adding somewhat large amounts of Mn., Al., Sn., &C., shows remarkable brittleness and decrease of elongation, by the precipitation of a brittle compound in the grain boundaries, at about 350 degrees centigrade when very slowly cooled after casting as in the case of large propeller casting. In view of this fact, in case of decreasing the amounts of alloying elements, its structure becomes α+β and accordingly the brittleness is avoided, but the strength is not sufficient.
Moreover, the Author confirms that, by the investigation of many examples of damaged propeller blades, many cracks due to corrosien fatigue have started from grain boundaries at the casting defects near the root's surface of propeller blades.
Therefore, for such material as manganese bronze for propeller, by the precipitation of different phases γ in grain boundaries as above-mentioned, its corrosion fatigue becomes inferior, the influence being greater when the structure is a single phase, say β from this point of view, the Author explains in this paper that without enbrittliug by slow cooling after casting, it consists structurally of two phases and furthermore it becomes necessary to select considerably high strength.
Now, after investigation under such consideration as above, the Author attained new alloy near to this object, but various tests being still continued, its mechanical properties is briefly shown in this paper.

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