Jakob Kunz

Flow Through Submerged Orifices

From the measurements of F. E. Giesecke on the flow of liquids through submerged orifices two definite laws have been deduced. When the diaphragm is completely closed, the liquid flows backwards along the wall of the tube, and forward in a central vein, the radius of which has been calculated for laminar and turbulent flow. The theory by v. Karman for turbulent flow has been applied to a tube of circular cross section. It is shown that both the backward flow and the jet issuing from the orifice are unstable. By an experiment it is made evident that a jet may sometimes describe a spiral motion.

XXXIX. The ionization of cæsium vapour by ultra-violet light

Abstract A new method has been applied for the determination of the photo-electric effect of caesium vapour. The photo-electric current has been amplified by a G.E. F.P. 54 amplifier. The coulombs liberated per erg of the incident beam and the atomic ionization coefficient have been determined for wave-lengths between 3130 and 2400A, and for three temperatures of 25°, 75°, and 125° C.

A Photoelectric Valve

The object of this experimental investigation was to determine the nature of the valve effect. After the description of the valve some characteristic and photometric curves are given. Sensitivity curves are then described which show the relation between the wave‐length and the photoelectric current per unit of light energy. These curves show distinct maxima, like ordinary photoelectric cells; this character of the sensitivity curves support the theory that the effect is primarily a photoelectric phenomenon connected with space charges. Other assumptions are shown to be untenable. Some additional phenomena, expecially of the dark current, and experiments with various modifications of the valve are reported.