Japan commenced drilling on Sakhalin in 1919, by means of rather primitive methods. In 1921 diamond drills and rotary rigs were added, and in 1923 cable tools were used. In 1925 work was almost suspended, pending treaty negotiations with Russia. Japan has prospected 13,000 acres of oil-bearing land on the eastern shore, a very small part of the oil belt which extends 250 miles along the coast. By terms of the concession from Russia in 1925, Japan is to prospect 300,000 acres which are to be divided into claims ranging from 40 to 100 acres, and arranged checkerboard-fashion, the alternating claims being retained by the Soviet Government, which may lease to a new applicant of any nationality. Results accomplished by Japan are encouraging for further exploratory work. Thirty one holes have been drilled; 5 were dry; 17 showed oil; and 9 were producers, ranging from 9½ to 189 barrels a day. In the 8 oil fields of Sakhalin, oil has been found at depths ranging from 100 to 2,984 feet. Japanese geologists have proved the presence of anticlines postulated by Russian geologists. The oil is used as fuel for Japanese destroyers.