Abstract
Coal seams in Ohnoura area contain a great many of Matsuiwa, and these obstacles are usually taken away by means of drilling and blasting. Electric drill can not overcome the above Matsuiwa, and therefore it had been already replaced by pneumatic drill which is more powerful and also more free dangers. To work coal by blasting is to be possibly avoided, and many pneumatic picks are employed in faces in order to decrease number of dynamites to be used for blast. Adaptation of coal cutter was thrown obstacles in the way by existence of the above mentioned fossil remains, but one set of cutter in 1929 and 6 sets in 1932 were adopted and these are now indispensable in spite of the special condition of coal seam.
