ing door, so that the amount of air passing into the split can be readily regulated. This door should be provided with a padlock or some other form of fastening, to secure it in any position the mine boss may think necessary.

Brattice cloth is used largely in place of doors and regulators to throw a portion of the ventilating current up through each breast. It is hung across the gangway from the mine timbers, reaching down to within one, two, three or four feet of the road-bed. It is also largely used in place of a brattice for throwing the ventilating current into the face of a breast or heading.

The law requires (Sec. 7) "not less than fifty-five cubic feet per second of pure air, or thirty-three hundred feet per minute for every fifty men at work in such mine, and as much more as circumstances may require, which shall be circulated through the face of each and every working place throughout the entire mine, to dilute and render harmless and expel therefrom the noxious, poisonous gases to such an extent that the entire mine shall be in a fit state for men to work therein, and be free from danger to the health and lives of the men . and all workings shall be kept and there shall be an in

clear of standing gas; take airway of not less than twenty square feet area, and the return airway shall not be less than twenty-five square feet."

With the exception of a few shallow non-fiery mines depending upon natural ventilation, the amount of air circulated is rarely less than four or five times the amount specified in the act. The operative clause of the act is that following the specification of thirty-three hundred feet, &c., viz: "and as much more as circumstances require."

Even when there is no danger from explosive gases a larger amount than this is necessary to quickly clear the atmosphere after blasting. Thirty-three hundred feet circulating through an airway of twenty square feet,—the smallest area allowable,-requires a maximum velocity of but one hundred and sixty-five feet per minute.

In the Wilkes-Barre district from 200,000 to 250,000 cubic

feet per minute is circulated through some of the most fiery collieries.

In the shallow basins of the East Lehigh district many mines are entirely dependent upon the natural ventilation. When the workings are shallow, the amount of gas insignificant, and the mine has several openings at the surface, the natural ventilation is generally sufficient, but in summer it is often very sluggish, and a fan or furnace may be absolutely necessary in extremely hot weather.

Safety lamps.

The use of safty lamps is generally restricted to the work necessary in opening new workings. It has been repeatedly shown that none of the so-called safety lamps insure safety. They may cause an explosion when the ventilating current has a velocity exceeding four or five hundred feet a minute, they give a very poor light, and it is difficult if not impossible to prevent the miners from opening them.

The feeling of a majority of careful, well-informed miners is well indicated by the following remark made in my presence by an old miner: "God save the man when the gas will fire inside his (safety) lamp, for he'll never get out to tell it."

In driving gangways, airways, shutes and cross-headings to open new workings in gaseous coals, safety lamps are very generally used, also in inspecting working places where accumulations of gas may be expected, but there are few mining engineers willing to adopt them for mining.

Naked lights are almost universally used for mining, and to insure safety, it is therefore necessary to pass a sufficient ventilating current to dilute the gas and render it harmless.

This is generally very thoroughly accomplished throughout the region, and with proper care on the part of the miners and other inside employés explosions would be very rare.

Explosions now generally occur, not because the ventilating current is insufficient, but because it is not properly

thrown up into the face and top of each working place where explosive accumulations of gas may occur.

It is entirely unnecessary to introduce into this report any information concerning the construction and relative merits of different forms of safety lamps, or to discuss the conditions under which they afford a certain degree of protection, as the literature on these subjects is already quite voluminous.

It will, therefore, be sufficient to state that nearly all colliery superintendents and engineers now unite in the belief that safety lamps should never be used for mining,-in other words, where the ventilation is insufficient to make the use of naked lights perfectly safe, mining should be suspended, and that they should only be used in development work, (gangway driving, etc.,) and for examining the workings for gas, and erecting brattices, etc., to drive out any accumulation of gas that may be found in the breasts. The use of luminous paint has been suggested as a substitute for safety lamps in gaseous workings and headings, but I do not know whether it has been found suitable.

Steam-jet ventilation.

Ventilating by means of steam jets turned into the upcast was but a few years since a very common practice, especially in the eastern portion of the Wyoming district. I do not know that any collieries are so ventilated at present.

In shaft and slope sinking and during the opening of new workings, this method of securing a ventilating current is very often used with good results.

Furnace ventilation.

Prior to the passage of the Mines Ventilation act this was the principal ventilating method, but it has since been almost entirely superceded by the use of fans.

The law forbids the use of furnaces for ventilating when thebreaker and schute buildings are built directly over and covering the top of the shaft," (upcast,)—some en

gineers think the law should absolutely prohibit furnaces underground.

Only a few furnaces are now in use, most of which are located in the western part of the Wyoming basin.

It will not be necessary to enumerate the reasons why fans are now so generally preferred to furnaces, as these are obvious.

It has repeatedly been shown that for shallow workings a properly constructed fan will give a higher ventilating duty (water gauge or pressure amount of air per minute) than a furnace, but that for very deep workings the furnace will give the best results. Few if any of our anthracite collieries have yet reached this depth, and when they do it will be found that the objections to furnace ventilation will be even greater than at present.

Fan Ventilation.

Fans of several different forms are used; they may be divided into two principal classes, viz:

1. Open running.

2. Closed periphery.

Open running fans (open around the whole circumference) have been largely used throughout the region, but are now generally replaced by closed fans embodying the essential features of the Guibal.

Some companies and individual operators still adhere to the open running fan. Thus all the fans (with one exception) in use at the collieries of the Delaware, Lackawanna and Western company are of this type.

It is conceded by a very large majority of mining engineers that open running fans necessarily waste a large amount of power by permitting a reëntry of air behind each vane, and also from exposure to high winds.

Many mine bosses are still imbued with the idea that open running fans must give the best results because they allow the air to escape freely from all parts of the circumference.

There are some details in the construction of the closed fans of Guibal type, now commonly used, which demand attention. I will note them in the following order :

1st. The spiral casing, shroud, or housing.

2nd. The inclination of the blades, paddles, wings, or

vanes.

3rd. Curvature of the blades.

4th. Width of blades.

5th. The shutter.

6th. The expanding chimney.

Perhaps the most important and distinguishing feature of the Guibal fan is the spiral or circular and spiral housing. In this the fan differs from all others, (except the Schiele,) for nearly all inventors patenting improvements on the primitive radial winged fan, specifically claim the free exit of air from all points on the periphery, whereas the Guibal delivers all its air through one orifice.

Great differences exist in the form of casing now used, some engineers preferring the shroud spiral throughout, others preferring it partly circular and partly spiral. Three forms are in common use: 1. Complete spiral, commencing at the throat (discharge) and expanding regularly throughout; 2. Upper half circular, spiral commencing 180° (opposite) from the throat; 3. Three fourths (or thereabouts) circular, spiral commencing opposite the lowest part of the fan, about 270° from the throat.

From the results obtained with several large fans with various forms of shrouding, I should judge that it is not necessary to extend the spiral around the whole circumference, that one half or more, 180° to 220°, may with advantage be made circular and the angle subtended by the spiral need not be more than 130° to 160° to give excellent results.

When the spiral is too short the discharge "jumps" from one segment to that next it, occasioning a decided jar. If this is alone considered it is evidently best to use a complete spiral, but a certain loss in the velocity of discharge occurs in fans so constructed (from friction, reëntries, etc.).

For this reason it seems best to construct the casing partly circular and partly spiral, the length of spiral being just sufficient to prevent the discharge from perceptible "jumping" from one segment to that next it.

The blades are made straight or radial, inclined back