district. In some cases the State inspectors have made certain rules for placing timbers in advancing rooms and drawing pillars. Where such rules have been made, or there are mine rules, they should be carefully followed. But these rules are not always sufficient; they cover the average case, but not an extreme or special condition—that is, it may be the rule of the district or mine to set two or three lines of props in a room, the props to be not over 5 or 6 feet apart, whereas in some rooms four or five lines of props may be necessary.

It is important to set the props at regular intervals and in some places to set extra props as they may be needed. If the roof seems to be in bad condition, do not hesitate to set a temporary post at the face to protect yourself while loading a car. Timber the place, if necessary, even though the post is in your way. Don't wait until the car is loaded, for the roof may fall on you. Keep proper tools on hand with which to do timbering.

When you are undercutting the coal, especially in a room, do not mine an indefinite width and depth without setting a block or sprag; the same car applies in top mining; if the roof is insecure over the mining, put blocks or posts under the roof as you proceed with your cutting.

Do not neglect to timber your place properly, even if you are in a hurry or feel that the top is all right because it usually is good, nor neglect to do so because timber would not allow you the same freedom to work. This neglect, if continued, will result in some one being hurt or killed.

One of the things that causes a large number of accidents is the "draw slate " in the upper part of the coal bed or just above the coal. In the Pittsburgh district this is called merely "slate; " but it is a slate" (really a clay shale) that in many places is hard when first exposed to the air, but rapidly softens and falls. Props will not keep it up; that is, it will "cut" around the head of the prop or cap piecę. Therefore, the best thing to do is to take it down immediately and stow it in the gob. When similar "draw slate " is found in mines in other districts no time should be lost in pulling it down.

In coal mines in France, which generally have a weak shale roof, the rules require that the props shall be placed not over 1 meter (31 feet) apart each way, and that there must be hitches cut in the coal face and straps or bars put in, supported by the props behind, before the miner is permitted to undercut the face." The good result of this law is shown by the records of accidents in the French mines. In spite of the poor roof, the number of accidents from roof falls in

a The bars extending at right angles to the face are usually long enough to be supported by two posts, so the face end is supported by the middle post.

proportion to the number of underground employees is lower than in any other country.

FALLS OF ROOF OR "SLATE" IN DRAWING PILLARS.

Drawing or pulling pillars requires experience and skill. If you have both, you may do this work. Otherwise you should not go into pillar workings without an experienced partner, or "buddy." No matter how much experience you have had, never neglect to set a line of "breaker props" so placed that if the roof weight comes on suddenly the line of props will break the roof there and prevent its breaking off at the edge of the pillar and burying you.

A common cause of injury from falls is the attempt to recover loose coal in the gob or goave. Unless there is timber protection for the miner, this should not be attempted. The recovery of props from the gob is a good thing to do if you are careful, but you should use chains and levers, so that you will be in a safe place when the prop is drawn out by the chain.

EFFECT OF EXPLOSIVES.

Great damage is done to a roof by the use of too much explosive for a shot and by not placing shots properly. If the hole is drilled too close to the roof, the blast tends to shatter it. Do not place the shot too near the roof. If the coal is not undercut or properly sheared, a great deal of the force of the explosive is spent in shattering the coal and sometimes the roof. Also, props may be blown down. Therefore "shooting off the solid" is an unsafe practice; it not only causes damage to the roof but is liable to result in blown-out shots and hence in explosions of coal dust.

You should watch closely to see that you use just enough explosive to bring down the coal. This will not only lessen the cost of the explosive and increase the proportion of lump coal, but it will lessen the risk of accident from an explosion or fall of shattered roof which might kill or cripple you.

When you go back after firing a shot it is particularly necessary that you thoroughly test the roof in the way previously described. You should not go back under any condition while the smoke is thick, both on account of the poisonous gases and because you can not then properly observe the condition of the roof or whether props have been thrown down.

FALLS OF COAL.

In three of the States that have large outputs of coal the figures for the calendar year 1914, as compiled by the Bureau of Mines, show these totals: In the Pennsylvania anthracite field 62 men were killed by falls of coal out of a total of 228 killed by falls of all kinds. In the Pennsylvania bituminous fields 44 were killed by falls of coal,

as compared with a total of 233 killed by falls of all kinds. In West Virginia none was killed by falls of coal, though 220 were killed by falls of all kinds. In Illinois 20 were killed by falls of coal out of a total of 69 killed by falls of all kinds. In these three States 126 men were killed by falls of coal out of a total of 750 from all kinds of falls, or 17 per cent of the total. The number injured by falls of coal is much larger than the number killed, usually three or four times as many.

Figures compiled by the Bureau of Mines indicate that in the calendar year 1914 the number of men killed by falls of coal (other than roof coal) in the entire country was 146 out of a total of 1,131 killed by falls of all kinds, or about 13 per cent. In the bituminous mines of the country the proportion of deaths from falls of coal to deaths from falls of all kinds was 84 to 903, or about 9.2 per cent; in the anthracite mines the proportion was 62 to 228, or about 27 per cent. The higher proportion of deaths from falls of coal in anthracite mining evidently was due to the steeply dipping coal beds.

The responsibility for preventing accidents from falls of coal is almost wholly in the hands of the miner. Most of these accidents occur through failure to block or sprag the coal while undercutting it, or, in a thick seam, while slabbing it off. The miner working among the lumps of coal may have his foot caught when a large mass of coal rolls over. There is particular danger from rolling coal in pitching seams, where the face may sometimes break and "run.”

Every miner knows that before starting to undercut the face, either by pick or by machine, he should carefully block the coal. This takes only a few minutes, and is a most necessary precaution. It also helps to keep the coal from spalling off if there is any weight from the roof, and tends to make the coal break at the back of the cutting, so that all the coal undercut is more likely to come down, instead of chopping off at the front when blasted, or, in long-wall work, when wedged. As you continue the undercutting you should put in blocks or more sprags. When you are ready to bring down the coal, knock out the sprags in order, starting at the inner end, so that you may not be caught between the coal and the gob in case the coal rolls over in a block. Special care needs to be taken in long-wall work, as in the northern Illinois district or the Canyon City (Colo.) field, where the long-wall system is employed, and there is little room between the face and the gobbed material. In a thick seam particular care must be taken in slabbing off coal that is high above your head.

SUGGESTIONS FOR FOREMEN AND ASSISTANT FOREMEN. Your positions carry great responsibility in caring for the mine and in caring for the lives of the men under your direction; the prevention of falls of roof is one of your most important duties. The responsibility of taking care of the roof in the entries, headings, or pas

sageways is yours. Unsafe roof in these places should be promptly attended to, and making it safe should be considered more important than getting out coal.

In keeping rooms and working places safe you share responsibility with the miner, except that it is your duty to see that timber supplies and tools are promptly furnished at the request of the miner, or as your own inspection has shown to be necessary. Systematic records should be kept of the supplies furnished each miner, and it should be a matter of suspicion that requires inspection if the miner is not using at least the average supply of timber furnished other miners. Dealing with a large body of men, you will always find a certain number of miners careless of their own safety. These men should be closely watched, and any miner who persists in not using the necessary amount of timber should be given other less dangerous work to do, or should be placed as the partner or "buddy" of a more experienced and careful miner.

It is sometimes thought because the roof is strong that little or no timber is required. Such mines or places are often the most dangerous, because when a loose block of roof is undermined there is no protection. Where the roof is good there is a tendency for the miners and the foremen to become careless. You should bear in mind that you must always be prepared for the unusual condition. The loss of one life or the crippling of one man will pay for a vast amount of timbering, not only from a humanitarian standpoint, but in dollars and cents.

INSPECTION OF WORKING FACES.

Constant inspection of the working faces is of the utmost importance. The mining laws of some States specify that the foremen or inspectors shall inspect the face at least once in two days. This is not often enough. It is far better, if the work can be so arranged, that an inspection be made every day by the foreman or assistant foreman in addition to the preliminary inspection by the fire boss; and it would be still better if inspections were made several times a day-if not by the foreman or pit boss or his assistants, by special inspectors or face bosses.

When there are a large number of miners who do not speak English, you should either learn their language sufficiently to explain how and where the props are to be set, or should have an interpreter explain to the men what is required in timbering, as well as in other matters pertaining to safety. In such cases it is doubly important that a foreman who orders additional timbers to be set should return to see that his orders have been obeyed.

There is an excellent system, which has been used to some extent in this country, by which the supervision of the workings is divided,

one foreman or "face boss" being placed in charge of each district, for which he is responsible to the head foreman or underground

manager.

IMPROVEMENT IN METHODS OF TIMBERING.

It should be your constant thought to improve the methods of timbering so as to prevent accidents. Sometimes the method of mining is improper and affects the method of timbering. This is particularly true in machine mining and in drawing pillars. Where breast machines are used a large amount of space is required between the face and the nearest timbers. In many cases temporary props should be set up, and reset as the undercutting proceeds. There is particular danger in machine mining when the work is so subdivided that no one man is responsible for the condition of the timbering, either temporary or permanent, in any one room or entry.

You should arrange this work so that the timbering will be carefully looked after, and some one will be responsible for each room and entry head, and you should not permit loaders to enter a working face unless there has been a preliminary inspection made of the roof. Many foremen have done excellent work by managing the timbering so as to keep down the number of accidents from falls in their mines, but in the greater number of mines, as shown by inspection and by statistics gathered by the State inspectors, insufficient precautions are taken.

In steeply dipping coal beds there are added dangers from falls of roof or coal. A large fall at the face may knock out many props. Where accidents from this or similar causes have occurred frequently, you should try to see whether the method of mining is the safest that can be adopted; that is, if open rooms are run straight up the pitch, see whether inclined rooms may not be used, or whether the gob (goave) may not be filled by waste rock, or by flushing in refuse or sand, as is done in many European mines in advancing work, and in mines of the anthracite fields of Pennsylvania in recovering pillars.

THE LAW IN PENNSYLVANIA.

The following extract from the bituminous mining law enacted in Pennsylvania in 1911 is printed here to show the measures taken by the largest coal-mining State to compel miners and foremen to be careful and to watch the roof:

BITUMINOUS MINING LAW OF PENNSYLVANIA, IN FORCE 1911.

ARTICLE 25, RULE 1.-The miner shall examine his working place before beginning work, and take down all dangerous slate, or otherwise make it safe by properly timbering it before commencing to mine or load coal. He shall examine his place to see whether the fire boss has left the date marks indicating his examination thereof, and if said marks can not be found it shall be the duty of the miner to notify the mine foreman or the assistant mine foreman of