encouraging the mining industry to experiment with those methods. of support which differ from conventional methods. I mean, the posting and the regular, standard methods.

The principle involved in this method of roof control is the prevention of initial sag and subsequent failure of thin bands of roof strata that lie above coal beds by reinforcing the strata with steel rods as soon as the roof is exposed.

With your permission, Mr. Chairman, I know that you and the members of this committee will be very much interested in seeing a device that we have which demonstrates this principle.

I would like to have Mr. George Grove, our supervising engineer at Pittsburgh, Pa., come forward, with your permission, and just give the committeee a practical demonstration on this method.

Mr. GROVE. This is a representation of a mine roof in various strata and layers above the coal bed represented by strips of lucite plastic material.

Mr. KELLEY. The coal roof is represented by what, Mr. Grove?

Mr. GROVE. Lucite, just as an illustration. There are different layers. It is not a solid. These are layers about one-eighth of an inch thick. This illustrates a mine post under each end of a working place, or an opening in the mine.

If weight comes on that roof from above, the entire stratum bends, as you can see here, and that initial sag puts the roof under a strain, and it starts disintegrating in the center and near the posts where it is held, and the more air, moisture, and so forth that comes in contact with the roof, the greater the liability of roof collapse and roof falls. Now, if these lower bands can be kept from moving and that initial sag can be kept from taking place, that upper band also cannot move. And this suspension type of support is usually applied by two methods.

Now, it may look to you from there, and to me from here, too, for that matter, as though those rods in there are threaded. But they are not. The appearance comes from these lucite strips through which they pass. There are no threads on those, thought. They are absolutely straight, smooth rods.

What happens there is that these rods are put up into the strata which they pass. There are no threads on those, though. They are spread out at the top like an expansion bolt so that they stay in the hole. Then a nut is screwed on the bottom, and the objective is to prevent the entire mass from moving, or certainly the lower portion of it from moving, because if the lower layer, the exposed layer, cannot move, nothing in the top can move.

Now, we will place that same weight on with the rods in it and you will notice there is absolutely no movement. And that is brought about solely by those suspension-type rods.

Another method of putting up those rods is to have them straight, up and down, instead of on an angle.

Mr. KELLEY. Those rods are put in the strata right above the coal bed?

Mr. GROVE. They are put into the roof, Mr. Kelley. Holes are drilled, the rods are forced up; they are hit on the end to widen out the expansion device on the end so that they have a good grip on the inside of the hole. Then either discs or channel irons are bolted on the bottom, and that holds the whole thing from moving.

Now, this works absolutely just the same as this one.
Mr. BAILEY. What about the question of cost there?

Mr. GROVE. The cost is not any greater, probably not as great as it is with conventional type of timbering where heavy timbers must be set close together.

Mr. BAILEY. To what extent do you have this in operation?

Mr. GROVE. It is quite widespread at the present time. We cannot keep up with the demand all over the country.

Mr. BAILEY. Do you get any demands?

Mr. GROVE. Very much so. We cannot keep up with the requests and demand for devices and how to install them, and checking up on them after they are installed. Some unbelievable effects have occurred. In a roof that was almost impossible to hold with conventional methods of timbering, they have successfully been held over a period of a year without a single roof fall occurring. That is, the advanced workings, too; not only the back, but the advanced faces.

Mr. KELLEY. Do you use that at the exposed surfaces?

Mr. GROVE. We can use it anywhere, Mr. Kelley. Now, it may not be used in all types of roof. But the results that have been obtained are beyond our expectations.

Mr. KELLEY. How long are those rods?

Mr. GROVE. The rods are about 7 feet long, in almost all cases, and 1 inch in diameter. The rod is split with a wedge in the end, and as the rod is forced up, that wedge is driven down, and widened in the form, as I said, of an expansion bolt on the end so that it gets a good grip at the top end of the hole and cannot move. That is the objective.

Mr. KELLEY. It is like an expansion bolt?

Mr. GROVE. It is on the same principle. It is not a bolt; it is just a widening of the rod itself, and a widening of the rod and forcing that wedge at the top end of it.

Do you want any more, Mr. Forbes?

Mr. FORBES. Unless the Congressmen have something they would like to ask. I thought they would be interested in it.

Mr. KELLEY. We are glad to see it.

Mr. FORBES. It will give an idea of what we are trying to do to prevent this terrible toll of fatal accidents from roof falls.

Mr. BAILEY. About what percentage of that comes from those falls?

Mr. FORBES. Over half, Mr. Congressman, and about one-fourth of the nonfatal accidents.

Installations supervised by Bureau of Mines personnel have been made in coal and ore mines, and results indicate the method to be quite successful. Inasmuch as this method largely eliminates the use of timber sets, collars and legs, and posts, it is of particular value in mechanized mines where dislodgment of standard supports is likely to result in a fall of roof and possible fatal injury to persons in the immediate vicinity. The widespread interest shown by the mining industry in this new method together with its approval by State mining departments and successful application in many mines. is proof of its great possibilities in reducing accidents from falls of roof and coal.

This, Congressman, will answer your question. To date, no rooffall accidents have been reported in areas of mines where the suspen

sion roof supports are used exclusively, and some companies have adopted the new method as standard practice throughout their

mines.

Mr. BAILEY. Can I ask another question here?

Mr. FORBES. Yes.

Mr. BAILEY. Is there any such law that would require their installation and use?

Mr. FORBES. No; there is not; just recommendations. Under our Federal Mine Safety Code, of course, these would be recommendations. This is something relatively new.

Mr. BAILEY. One more question. Do you know of any State bureaus of mines that are requiring the use of them!

Mr. FORBES. I do not know of any-I really do not know. I know they are going right along with us in our research and investigative work in connection with it.

I might say here that there is one mine-I do not think it is necessary to mention the name of it-a large producing mine, that produces in the neighborhood of 5,000 tons a day, that adopted this method 9 months ago, and to date they have not had a single roof fall, let alone a single accident from roof falls.

Now I want to say that we are keeping our fingers crossed on this. It is necessary for our engineers to go to these different places and show them how this method should be properly applied to their particular roof conditions.

Mr. KELLEY. As a matter of curiosity, where did you develop that method?

Mr. FORBES. It came from the lead districts of southeast Missouri, and then was taken up by a coal company near East St. Louis, Ill. We picked it up from there and started pushing it, and made certain refinements on the method to date. We are still finding some things out about it.

Additional investigative work conducted by personnel of the Coal Mine Inspection Branch includes:

(1) Special ventilation studies relating to the use of auxiliary blower fans with tubing, and the volume of air in the last open cross-cuts of entries. Ventilating pressure surveys are made at the request of coal-mine operators with a view to improving the efficacy and quality of ventilation.

(2) Cooperation with the Health Branch in conducting surveys of air-borne dusts in coal mines.

(3) Experimental work in the use of permissible explosives and blasting devices at the request of mine operators to the end of eliminating dangerous black blasting powder in underground mines.

And I just hope to God that the day comes when we will eliminate entirely the use of black blasting powder from coal mines.

Mr. KELLEY. Some States prohibit, do they not? Is not Pennsylvania one of them?

Mr. FORBES. Under certain conditions, yes. Pennsylvania is pretty much in the lead in that respect.

Mr. GROVE. In Pennsylvania it is only in the gassy mines.

Mr. FORBES. Only gassy mines; that is right, Mr. Grove.

Mr. GROVE. Why, West Virginia does more than Pennsylvania does. Mr. FORBES. This continues:

(4) Investigation of coal mine disasters to determine causes and means of prevention. The personnel of the Coal Mine Inspection Branch assists in rescue and recovery work following disasters.

(5) Investigation of underground electrical hazards. Requests for investigations generally originate with mine operators who are interested in increasing the safety and efficiency of their electrical installations.

Now I come to the portion where I thought I wanted to give the committee this background material for the material that follows. This deals with inspections under Public Law 328.

I have here, Mr. Chairman, a copy of Public Law 328 passed by the Eightieth Congress, and I think it might be well to have that inserted in the record, as well as a copy of Public Law 49.

Mr. KELLEY. A copy of Public Law 49 was inserted in the record this morning.

Mr. FORBES. That is all right.

Mr. KELLEY. And I would like to have Public Law 328 inserted at the same point.

Mr. FORBES. Very well. I have it here, and I have the discussions that the committee made when they passed it. And with your permission, I will have them introduced in the record.

(The material referred to above appears in the record at p. 8.)

Public Law 328, Eightieth Congress, approved August 4, 1947, and effective for 1 year, provided that the Secretary of the Interior, acting through the Bureau of Mines, if upon inspection of any coal mine pursuant to the act of May 7, 1941, finds that the safety standards set forth in the Federal Mine Safety Code with respect to major hazards in underground bituminous-coal and lignite mines are not being observed, shall notify the owner or operator of such mine and the State agency charged with enforcement, of the Federal inspectors' findings and recommendations and request the mine owner and State agency to report the action taken to correct the hazards. The law required the Secretary of the Interior to submit quarterly reports to the Congress. Public Law 328 recognized, by inference, the Federal Mine Safety Code as the basis for determining unsafe conditions and practices in the bituminous-coal and lignite mines of the Nation. Under this law, all enforcement of safety measures was left to the State agencies, and the purpose of the law was to place upon the States the burden of making the mines safe and keeping them safe for the protection of men underground until Congress had an opportunity to study the problem thoroughly. The Congress made it clear that if the States do not guard the safety of the miners, the Congress would act. This act expired in August 1948.

During the year in which Public Law 328 was effective, 2,184 underground coal mines were inspected. These represented 72 percent of the Nation's coal production. Of these, 1,934 were reinspected to determine the extent of compliance with safety recommendations made during the first inspection. According to information gathered by the Federal coal-mine inspectors, a total of 27,313 hazards identified in Public Law 328 were observed during the first inspection; during the reinspections Federal coal-mine inspectors reported that 34 percent of the hazards were eliminated, 15 percent were corrected in part, and no corrective action was taken with respect to 51 percent of the violations.

By employment groups, the average compliance in underground bituminous coal and lignite mines during the year the law was in effect was reported by Federal coal-mine inspectors as follows:

In 405 mines employing less than 25 men, the percentage of compliance with Federal recommendations was 25 percent.

In 710 mines, where the employment ranged from 25 to 99, the percentage of compliance was 31 percent.

In 551 mines where the employment ranged from 100 to 299, the percentage of compliance was 38 percent.

In 160 mines with employment from 300 to 499, the percentage of compliance was 39 percent.

In 108 mines with 500 and over of employment, the percentage of compliance was 47 percent.

Based on the number of men employed, the record indicates that the larger the mine, the better the compliance with Federal recommendations to correct unsafe conditions and practices. In other words, the smaller mines were more hazardous than the large mines, which in general is borne out by the accident records.

Mr. BAILEY. Why was this just for a period of 1 year? Was it an experimental law?

Mr. FORBES. Yes. It started, Congressman, as a resolution in the Senate and then a joint resolution in the House and passed just as an experiment to see what action could be expected during that year. Mr. BAILEY. Did the Bureau renew its request for a continuation of the legislation?

Mr. FORBES. Not to my knowledge, Congressman.

Mr. BAILEY. In your opinion, would it serve a good purpose?
Mr. FORBES. It probably would.

The investigation, covered by Public Law 328, discloses that some progress was made in reducing hazardous conditions and practices in the Nation's underground bituminous coal and lignite mines, but it also indicates much room for improvement in reducing the principal causes of accidents in underground mining operations.

The effectiveness of Federal inspection of coal mines under Public Law 49 is reflected in the mine accident experience since Federal inspections began. Accident data covering coal mines were included in appendix B. The first full year of Federal coal-mine inspection was 1942. Based on man-hours of exposure, some improvement is indicated in the fatal and nonfatal injury rates since that year. Comparative average accident rates on a million man-hours of exposure basis for the 9-year period immediately preceding Federal coal-mine inspections and the 7-year period of such inspections are as follows: For the years 1933-41, the fatal injuries in bituminous mines were 1.45; in anthracite, it was 1.62, or an average of the anthracite and bituminous industries of 1.48.

For the years 1942-48, when the Federal coal-mine inspection came into being, the fatal injury rate in bituminous mines per million man-hours was 1.25.

Mr. BAILEY. Would you explain what you mean by that 1.25?

Mr. FORBES. One and a quarter deaths for every million man-hours

worked.

Mr. BAILEY. It is not worked out on the basis of the men employed; it is on the basis of man-hour?

Mr. FORBES. Yes; on the basis of man-hours.