In the precent paper the author describes the investigations carried out in his laboratory as the following:I.Incandescent arc lampThe ordinary tungsten arc lamp hitherto introduced in the market can not be dis pensed with the complicated starting device.The tungsten incandescent arc lamp here described was invented by the anther with C.Matsuda, and is to be considered as the combination of the low pressure gasfilled in candescent filament lamp and the tungsten arc lamp.Incandescent filament serves not only as the ordinary incandescent lamp filament, but also as the ioniser of the gas between the tungsten electrodes.Steadifying resistance for the arc is inserted in series or parallel to the filament circuit according to the case may be. Thus in this lamp starting device is not necessary, contrary to the ordinary tungsten arc lamp, and when the lamp is switched on the supply mains, arc is started between the tungsten electrodes just as simply and easily as the ordinary incandescent lamp.Special protecting tungsten shields are provided to the terminals of the lead wires to protect against the bombardment of the ionised gas upon the incandescent filament.II.Low pressure gas-filled lampThe principal purpose of the ordinary gas-filled lamp is to reduce the evaporation from the incandescent tungsten filament, so that the lamp can be opered at much higher temperature than the ordinary vacuum incandescent lamp.But the convection loss is hereby introduced due to the filling gas, and it amounts to a comparatively high value. Low pressure gasfilled lamp is thus preferable if the corona discharge can be prevented by some simple means.To overcome this difficulty and provent the corona discharge, a small conducting wire net or mica plate shield is introduced in the path of the ionised ions between the filament terminals.Thus the net or plate acts as the electrical and mechanical shield protecting against corona discharge and against the bombardment of ions.III. Semivacuum lamp.Another low pressure gasfilled lamp, called “Semivacuum lamp” or “Economy lamp”, having a special protecting device against the corona discharge was invented at the Aoyagi Lobaratory.Nitrogen gas being filled at the pressure less than about 50m.m. of mercury.The nitrogen gas in the bulb is not introduced externally, but produced by the decomposition of a chemical, azide of alkaline earth metals, sealed in the bulb. The laboratory test for this lamp gives the better results compared with the ordinary gasfilled lamp, and its production cost may be reduced compared with the latter.IV. A new radiation photometer.The Aoyagi laboratory invented a new photometer to measure radiation, making use of the resistance variation of the two tungsten filaments sealed in the vacuum tube, due to the exposure of the radiant energy under consideration. The above two filaments form the two opposite arms of a Wheatstone bridge. The main advantages of the instrument are that it has great sensibility and no effect of room temperature.It is convenient to measure and to describe easily the light distribution curve, Rousseau curve, etc. by means of a given simple mechanism.V. A new radio tubeA new radio tube was invented at the Aoyagi laboratory, which gives a large electron current notwithstanding the small filament current and low filament temperature. The tube contains the vapour of zinc, cadmium or both which increases the activation of the filament.The production cost is much reduced by using the zinc plate or alike instead of the nickel plate.