By using a potential function, the general solutions for the effect of a cavity or a hole under some constant stresses at a great distance from the cavity in an infinite elastic body are derived from the results for a circular hole already studied in a recent paper. The constant stresses treated are the tensile stress, the shearing stress and the constant hydrostatic pressure in the cavity and the solutions are worked out for a spherical or ellipsoidal cavity and an clliptical hole.

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With a view of improving the piston ring, the amount of the radial pressure exerted by the piston ring on the cylinder wall was at first ascertained by means of a specially designed apparatus ; to which piezo-electricity of quartz was applied so as to get the configuration of the pressure distribution. Tests of the many sample pieces of commercial rings on markets, show that there is surprisingly a wide range of pressure irregularity which is naturally an undcsirable function for the efficiency and maintonance of the engine. In this paper, a ring which exerts a nearly uniform pressure on the cylinder wall is described and the maximum stress of the ring under working conditions is calculated mathematically, and a 3HP four cycle horizontal Diesel engine which is in the laboratory in our Institute was used for the experimental researches in connection with the effect of the pressure of rings on gas rightness, as well as for determining the frictional resistance between the piston ring and the cylinder wall.

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Most grabs of ordinary design have several disadvantages such as : 1. The course traversed by the grab is complex, 2. Handles and handlings are too numerous, 3. A large grab, therefore, is to be used in order to increase the capacity of the machine, 4. The larger the grab, the greater will be the power of the prime mover, 5. Owing to the jerk and vibration of ropes by which the grab is suspended, it is practically impossible to grab the material at an exact desired point within the scope, 6. Twisting and entangling of ropes have the effect to decrease the capacity of the machine and the life of the ropes, 7. There is a risk of over-winding of ropes on the top guide pulley, 8. It is necessary to gather and scavenge the remaining material after grabbing, 9. The position of the operator's cage is too high to have a good command of view of the material to handle, 10. It is very difficult to weigh the content of grab, 11. The automatic operation of the machine is impossible. In order to overcome all the defects mentioned above, I have deviced a new system, which I claim to be a novel one in its own way. The system is a combination of a grab and a conveyer, in which the grab moves in a vertical direction. A swinging chute which stands vertically by means of a counter-weight connected to it, is placed in the midway of the passage of the grab. When the grab handles material, and is lifted vertically up to a suitable position, the upper part of the grab lifts the counter-weight, and so the chute projects itself to the passage of the grab. After discharging its content, the grab is lowered accompanying the counter-weight of the chute, and the chute recovers its upright position making a free passage to the grab. The system further involves the guide-bars with operator's cage and scraping boards at their lower ends, for the vertical passage of the grab. The guide-bars themselves are also guided by a fixed frame, and are operated vertically by an operator according to the position of the material to be handled. In my machine I reduced the number of handles and handlings to an extreme limit, i.e. only to one, and thus succeeding to turn out a maching of an automatic operation which is almost impossible in all the machines of the similar nature now in use. Further-more the capacity of the machine is increased three to seven times the ordinary one with the same size of grab, and five to twelve times with the same power of the motor by which the grab is operated, leaving the weighing and the conveying to the conveyor combined to the system, which consumes only a small fraction of power required for the grab.

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