By making plastic replicas of snow, the writers measured the mass and number of falling snow crystals in the atmosphere. Experimental work was done in an igloo, half way up Mt. Taisetsu in Hokkaido, at an altitude of 1050m. About one thousand specimens Were obtained in the three winters 1950-52. This paper is concerned with the most interesting 34 specimens which were taken during a 12-hour period from 0000 JCT to 1200 JCT on 2 March, 1951. At that time, the air temperature and the crystal formation of falling snow varied very remarkably; the snowfall in this 12-hour period was 17cm in depth, which corresponds to 13mm of water. A small sheet of black paper or a clean slide glass for microscope was immersed for a moment in the 1-3 per cent solution of formvar dissolved in ethylene dichloride, and then was exposed horizontally to the falling snow crystals for 30 seconds. And replicas of falling snow crystals were obtained as shown in Figs. 3-19. The total mass and the number of snow crystals in the atmosphere were calculated from these replicas. The order of magnitude of the total mass was 102mg/m3 and that of the number was 104 particles/m3. The total mass of snow crystals shown in Table 2 seems to coincide with the liquid water content in the cumulus cloud.
A new combination of wind vane and anemometer for remote recording by means of telephone wire was-designed by the authors in the Meteorological Research Institute. As the test experiments had promised a fairly satisfactory performance, the equipment wasinstalled in August 1951 on Yakushima Island, about 60km south of Kyushu. The equipment has a transmitter, with a spring motor wound by the cup-anemometer, and an automatic scanning mechanism for indication of wind vane directions when the spring motor is released at every 200m wind course and rotates at a constant speed controlled by a governor. The wind speed is indicated by the electric pulses generated at every 200m wind course. The transmitter requires no electric energy source, and therefore purely mechanical incorporating electric contacts are required. The signals corresponding to the wind direction and wind speed are sent as electric pulses to the receiver and recorded by means of two helical cams which are started and stopped in synchronization with the effects by a governor of the same characteristics as that of the transmitter. In the 1. part the design and the construction are explained in detail.