An electrode for an electron gun and an electron gun using same are provided which make use of stable carbon material having small work function and which permit orientation control to be achieved and which can be manufactured at a low cost. Design elements that would otherwise be difficult to efficiently render three-dimensionally in real-time are prerendered for realistic visual effects, such as realistic shading, which correspond to various positions of the elements in a design space. 96 or more and contains no more than 30% by weight of particles having a sphericity of less than 0. Disconnect areas may be provided near the crossover point to allow selective disconnection of the conductors from the crossover point. The element for selectively blocking the bypass tube may be automatically response to a change in oil temperature or a change in oil pressure. The provision of a rotatable barometer allows the use of a barometric fluid of a density lower than that of mercury to be used, thereby enabling the use of mercury to be avoided.