Discussion

(The following discussion took place on this screen lecture in the dark.) MR. SHUBART: Would you give us a little .explanation as to the operation of this machine and what you are doing with it? MR. TESCHER: There is a 20- horsepower motor, rheostat, crusher, and a fan mounted on one base plate and operating on one shaft. The fan is overhung on the shaft. The only bearings you have are the bearings on each side of the crusher and the motor hearings. On one side of the ma- chine there is an opening for feeding shale. The machine is operated at 1,200 revolution per minute and as the shale is pulverized, the fan automatically exhausts fine dust from the crusher from an opening in the top of the crusher. The machine pulverizes 3,000 pounds in eight hours, reducing the materid to one hundred mesh. The last ma- chine we put in has been operating continuously fifteen hours a day for the past sixty days, without repairs of any kind. PRESIDENT LITTLEJOHN: Where is the machine in operation? MR. TESCHER. At the Royal mine. We have used ordinary mining ma- chine cable in local movements of the machines. This has enabled us to have twenty-two locations throughout the mines. The mine is highly gaesous, and the machines had to be placed on intake air. MR. SHUBSRT: What type of crusher do you use? MR. TESCHER. A No. 16 Universal, operating at 1,200 revolution per minute. M. SHURART: What material do you feed to it? MR. TESCHER: We have shale three-quarters of a mile from the mine. In the winter months we have been troubled with moisture. We build a kiln and get this shale and load it into the kiln for drying and then place it into a pit car and take it into the mine. The material must be dry. We have also used slate in the mine and have had good success. The slate at the mine is fairly hard. I presume, however, that the slate will probably carry a high silica content. MR. SHUBART: Mr. Harrington claims that silica does not do the harm, as was formerly supposed. MR. TESCHER: There is still a question as to whether it is harmful or not. PRESIDENT LITTLEJOHN: Are there any of these machines in operation closer than Aguilar? MR. TESCHER: There is one at the Alamo mine. Mr. Quealy also purchased a couple of them for use at his Wyoming mines. PRESIDENT LITTLEJOHN: Are there any other questions you would like to ask Mr. Tescher regarding his rock dusting machine while it is on the table for discussion? MR. DALRYMPLE, SR.: How many men does it take to operate it? MR. TESCHER: One man operates the machine. Sometimes we put the