The decrease in the power output of aero-engines due to altitude has been already computed by several authorities. Most of them proceeded with the law of Welter that the quantity of heat liberated by the combustion of gasoline sucked into an engine cylinder is proportional to the weight of oxygen carried in with the gasoline. In this paper, the same problem is treated of, though the final result is not much difference, a little more theoretically from the thermodynamical point of view. Firstly, the formula for the mean effective pressure is deduced in terms of the pressure p and absolute temperature T of the fresh charge, the compression ratio ρ, the ratio γ of specific heats of the working fluid and the temperature rise ΔT due to the internal combustion. The first two factors p and T depend directly upon the conditions of the surrounding atmospheric air and the other two γ and ΔT upon the chemical compositions of gasoline and the ratio of air to gasoline in the fuel mixture as well as the ratio of compression. All of these factors are then computed theoretically, the results of which are applicable not only to gasoline engines but also to other internal combustion engines. The retaining of the horse power of aero-engines at high altitudes can be effected by two different systems-namely, by supercharging or increasing the compression ratio. The author's formulae may be used for the calculation of the latter system, which is of more interest in commercial service as it has an advantage for increasing fuel economy rather than power output. The author's own device for increasing the compression-expansion ratio is also described. So far the richness of the fuel mixture has been taken as constant at all altitudes. The effect of the variation of the richness is finally considered. In connection with this, the theory of the altimetric corrector for the carburation is treated of ; it must be, however, modified by the results of many experimental researches.

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The spring under compressive load is liable to unstable state. A formula of this phenomenon is reduced in this paper, treating the spring as a rod with equivalent moment of inertia against bending moment, then the relations between length, load and stiffness are found by the Euler's theory of long column. The equivalent moment of inertia is approximately the multiplication of the moment of inertia of the spring wire into sinα/1・125, where α is the helical angle of the spring at the loaded condition.

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For boat and car engines, in these days, there are several horse power rating formulas recommended by authorities, for aero engines, however, we can hardly find any suitable formula. The aero engines being made a great progress for several parts, it is rather difficult to express the rating in fairly simple form. The writer at first assumed the brake mean effective pressure (ηp) as of the const. value with a view to get the only simple rating, that is to say, expressed the brake horse power as the function of cylinder bore (d), piston speed (S), and no. of cylinder (N), and selected the const. value by careful examination of modern aero engines. In conclusion the writer recommended the three rating formulas for Vertical & Vee, Radial, and Rotary engines.

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The ring discussed in the paper is of large diameter compared to its cross section. An analysis of the stresses is treated by the method of least work, not being the theory of curved beam, neglecting the tangential and direct normal strain. An example represented in a somewhat general form being solved, the cases from its combinations and special cases are illustrated herewith.

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The Spiral Casing is one of the heaviest pieces among the machine elements that constitute the Francis Turbine and it is also subjected to heavy stresses due to hydraulic pressure, sometimes accompanied with severe hammering actions. Owing to the complexity of the form, it is not easy to make beforehand the exact calculation on this subject, but I think it would be of some use even if we could get a rough estimation of the values os the internal stresses under possible working conditions and therefore have endeavoured to find out the approximate solution of this question. Below is disoussed the problom as an applied case of the formulae of the strength of curved beam and I hereby introduce a few cases of actual plants in this country as numerical examples.

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Actual internal combustion engine indicator diagrams are always different from those of theoretioal cycles such as Diesel cycle or Otto cycle. The Auther attributes this evidence to the difference of the state of heat supply in cycles and actual combustion (or explosion) of engines, and proposes a new cycle in order to make this clear, in which he treats the heat supply as a function of time. (Introduction) Now he deduces the relation among volume, pressure, and heat supply in a perfect gas as follows. Vdp+γpdV=mR/Kvqdt (Article 1) Solving and applying this to a state of medium in working cylinder, he gets the general formulas of new cycle. (Article 2) By substituting several practical reasonable values of volume and heat supply in the general formulae, he gets following practical forms. (Article 3) Case 1. Constant pressure cycle : -which suggests the ideal condition of heat supply for Diesel engines. (Article 4) Case 2. Constant heat supply cycle : -which nearly coincides with actual Diesel engine indicator diagrams. (Article 5) Case 3. New gas engine cycle : -which nearly coincides with actual gas engine indicator diagrams. In later part of this essay he describes several numerical examples for case 2 and 3. (Article 9 & 10) From these investigations, he finds that the cooling loss can be reduced considerablly by using Suitable Construction of Combustion space with respect to form, wall insulation & c. The further investigations are left for the future, but the new cycle, he says, will be useful for analysing actual indicator diagrams, and for improving actual engine performances. (Conclusion)

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The efficiency of the machining in the work shop much depends upon the heat-troatment of the tool-steel. This fact was first found cut by late Mr. F. W. Taylor and generally has been acknowledged. But, within the author's knowledge it is believed that the true meaning of the tempering of the high-speed-steel as the cutting tool has not been made clear. The tempering of the high-speed-steel is discussed in this paper, comparing with that of the Carbon-tool-steel. The tempering of the former not only gives the toughness to the steel, but increases the cutting efficiency of the tools, while it seems that there is a certain range of temperature to get the best results. From experimonts the author learned that the physical properties of this steel after tempering are much affected by the different kinds of quenching mediums, although giving practically the same hardness. He gives the explanation to the meaning of the secondary hardness of the high-speed-steel, but that of rod hardness is left for future investigation. In conclusion, he suggests the best tempering temperatures for the nature of the cutting tool, and the criterion to judge the quality of high-speed-steel by the degree of the secondary hardness.

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In order to make the analysis of beams less laborious, there derive four foundamental and five auxiliary formulas, proved by means of the semigraphio method. Six standard examples are fully explained by these formulas, not using higher mathematics. Four examples represented in a somewhat more general form are solved, being considered as Combinations or Special cases of the standard examples. Two examples of the continuous beam are explained Instly. One hundred twenty two formulas obtained from these examples may be applicable with less Inbour to numerous problems arising in practice.

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