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• OPTICS Optical Design.—Research has been done on the theory of high-performance optical systems and design methods in order to reduce numerical computation to a minimum, with some notable results. This work was undertaken initially under the direction of Dr. F. D. Cruickshank of the Tasmania University. Data on available English optical glasses have been examined for designing highly achromatic combinations. Optical Workshop.—Apart from making components for new optical systems, some reconditioning work is done, mainly on the highly skilled work of polishing scratched surfaces on photographic lenses. Optical Testing.—Special apparatus is under construction both for testing the general performance of optical systems and for evaluating individual aberrations. ELECTRON MICROSCOPE Several improvements in the electrical circuits of the microscope received from the makers are now being incorporated, and should improve its performance. Research, in conduction with the Dairy Research Institute is in progress on the action of bacteriophage on the bacterial " starters " used in the cheesefactories. Other work includes particle sizing of paint pigments for local industry, and of ceramic materials for the New Zealand Pottery and Ceramic Research Association, in addition to studies on soil colloids and spermatozoa of bulls. ELECTRICAL AND ELECTRONIC DEVELOPMENT AND TESTING Ultra-violet Radiation Integrators.—lntegrators of the original design were used to compare solar and sky ultra-violet radiation at Lincoln and Lower Hutt during July, 1949. No significant difference was detected, but instrumental inconsistencies appeared which could have obscured small differences. Accordingly a complete redesign was undertaken, and the resulting much-improved equipments will be used for further tests in 1950. Quartz-crystal-controlled Clock. —The first model has given long and satisfactory operation in the laboratory. It has now been transferred to the Seismological Observatory for use in the time service. A second model is complete except for a new oscillator incorporating a high-quality crystal which is expected from the United Kingdom. Quartz-crystal Preparation.—Techniques of activity measurement, X-ray examination, etching, plating, and wire mounting in vacuo have been developed, at the request of the Post and Telegraph Department. Mental Therapy Electric-shock Unit.—The prototype unit providing " brief stimuli" facilities, requested by the Department of Health, has been completed and delivered. Radiography Timer.—The automatic exposure timer for use in X-radio-graphy and photofiuorography, developed at the request of the Health Department, has been completed and delivered. Final adjustment is awaiting the convenience of the Health Department.

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