REPORT ON OCEANOGRAPHY 67 



Navy during the period of ten years beginning September, 1923. He 

 found that the visibiHty is excellent in low latitudes almost all the year 

 round. In high latitudes, poor visibility predominates, especially in 

 the summer months. In the Far East the Summer Monsoon is directed 

 from south to north, so the conditions will be favorable for advec- 

 tion fogs. In the colder half of the year, the obscuring snow in the 

 rear of winter cyclones on the northern sailing routes reduces visibility 

 as a rule (MGP, 1, 1950, 58-66). Based on the materials from the 

 same sources, he and Tsutsumi also discussed the seasonal changes of 

 daily frequency of squalls in the same area. He concluded that the 

 frequency of squalls is drastically large in the Equatorial belt east of 

 Longitude 125°E and south of Latitude 10°N, where the rainfall is 

 heaviest in the Pacific as mentioned by G. Schott in 1938 (MGP, 1, 1951, 

 296-301). 



In 1951, Hokodate Marine Observatory carried out the observations 

 of fogs around his northernmost island very close the polar front and 

 confirmed many of former conclusions on this phenomenon, together 

 with the fact that there are very few of the short period components in 

 the turbulence when the fog is very dense and the lapse rate of tem- 

 perature is small close to the sea surface (KJ, 4, 1952, 81-120). 



A statistical study was made by M. Hanzawa and T. Inous on the 

 influence of the variation of sea surface temperature and pressure on 

 the growth of rice crop (KH, 2, 1952). 



Instruments and Methods 



In 1950 K. Ono of the Japanese Hydrographic Office, Tokyo, de- 

 signed an electric shelf recording current meter. This instrument has 

 undergone several improvements and has been used in several areas 

 around the Japanese Islands with success. Another design with a photo- 

 electric cell tube is also published by T. Nan'niti though we have 

 not heard of its widespread use (MGP, 3, and 4, 1953, 286-294). 



In 1950 Nan'niti designed a lazy thermometer and tried a theore- 

 tical consideration on its time lag. 



S. Agari made a design to measure the deep water temperature on 

 deck by the use of an electrically controlled distant deep-sea reversing 

 thermometer. This consisted of a thin carbon thread sealed in a glass 

 tube. The electric resistance is measured by platinum electrodes at- 

 tached on this carbon thread. He made tests with both protected and 

 non-protected reversing thermometers (KJ, 8, 1953). 



Sliizuo Ishiguro is a very good designer and constructor of oceano- 

 graphic instruments. He designed a sea wave height recorder taking 

 advantage of the buoyancy of a cylindrical buoy placed in the water 

 (KK, 4, 1950, 45-53). 



