At the upcast-shaft, at Woodhorn colliery, the fan-drift is placed below the surface-level, and out of the way of coal-drawing, etc. The fan-drift is walled and arched, and the top of the arch is covered with stones and earth up to surface-level. The fan and its engine are placed some distance from the shaft and clear of the heapstead.

The shaft is enclosed, above the surface, by means of a rectangular framework, aaaa, built from iron-girders, bbbb, placed across the top of the shaft ; and four vertical iron-girders, aaaa, are placed at the corners of this rectangle. They form the skeleton-framework, and also carry the cage-buntons. cc, and rail-guides to a sufficient height for banking out. They are bolted to cross-girders, and the whole framework is firmly fixed to the pulley-legs. This arrangement of framework is, of course, very much like that adopted at most coal-drawing pits but as it is erected at the ventilating-shaft, the arrangement must necessarily be enclosed and made air-tight (Figs. 1, 2 and 3, Plate XII.).

Fig. 1 (Plate XII.) shows that the framework does not cover the whole of the shaft, being about 10 feet by 9 feet inside, while the diameter of the shaft is 15 feet. It will also be noticed that the centre-line of the framework is about 17 inches from the centre-line of the shaft. Consequently, there is more room at one side of the cages in the shaft than at the other, and the extra room is utilized for pipes, cables, etc.

The top of the shaft and the bottom of the framework is enclosed in a brick building, 52 feet long, by 17½ feet wide, and 25 feet high (Figs. 1, 2 and 3, Plate XII.). The walls are 2 feet thick, and the top of the building is covered with stout planks, d. Each plank is grooved along its sides, and fitted to its neighbour, an iron-strip being placed in the grooves so as to ensure a minimum of air-leakage. Flatsheets are laid upon and attached to the planks, and this forms the banking-out level. The brickwork is not carried above this level.

The framework is enclosed by rivetting sheet-iron, 3/16 inch thick, to the girders, forming a rectangular box which extends from the flatsheet-level to the top of the pulley-frame, and just below the pulleys. The height of the framework above ground level is about 55 feet. The top is also enclosed, with the exception of two holes, 12 inches in diameter, left for the passage of the winding-ropes and of the safety-hooks, when necessary.

To allow of the tubs being changed, wooden sliding-doors, ee, are fixed into the framework at the banking-out level, one door being placed at each end of each cage. These doors are fitted with iron projecting brackets, ff, and when a cage comes to bank it lifts up its own pair of doors, and allows the banksman to change the tubs. On the cage being lowered, the doors fall again into their places. Each door weighs about 1½ cwts.

The brick building, enclosing the lower portion of the framework, allows of cages being changed or repaired, horses or material being sent down or drawn out of the pit, without causing a great inflow of air to the fan from bank. The latter condition necessitates an arrangement of double doors, so that at least one may be closed while persons are entering or leaving the building. A wall, gg, 18 inches thick, is built across one end of the building, fitted with a doorway, h, 13½ feet high and 6 feet wide. This partition-wall divides the building into two parts, and a doorway of similar size, i, is built into the outer and adjacent wall. A pair of smaller doors, j and k (7 feet high by 4½ feet wide), are built into one side of the building, and are used by persons entering or leaving the enclosed building.

In order further to prevent access of air within the building, the framework is cleaded with wood, ll, and a pair of large doors, m, and a small door, n, are erected in the wooden cleading. This arrangement facilitates the opening and shutting of the outer doors.

There are six windows, with iron-frames, built into the sidewalls of the building. to admit light in the day-time. Electric lights are used for night-work.