Sources of illumination for ultra-violet microscopy

The paper describes experiences encountered in an attempt to find means for reducing the exposures hitherto necessary in ultra-violet microscopy. Amongst the subjects dealt with are quantitative measurements of the relative intrinsic brightness of spectrum lines given by various sources of radiation; methods of producing a monochromatic source suitable for this work; the steadiness of the illuminant; the effect on the definition of the image when a triple spectrum line is used as a source; the study of electrical conditions for the production of increased brightness of the spark, such as the effects of change in frequency, secondary potential, capacity, and energy input; and the production of a compact and inexpensive electrical unit for use with the ultra-violet microscope.