It is advisable to have boilers periodically inspected. To secure satisfactory inspection, which should be thoroughly effected every year, the boiler should be emptied and cleaned out, and all scale removed.

The flues should be thoroughly swept, and the fire-bars and bridges wholly removed. Care should be exercised in using disincrustant compositions, and, on the whole, there is nothing better than common soda or soda ash, and the blow-out tap should be used two or three times per day to remove deposit.

Safety valves should be made to blow slightly by lifting them every day at least, and gauge-cocks should be tested frequently every day, and especially first thing in the morning.

4

Low-water alarms should give warning when the depth of water over the crowns of the furnaces is not less than inches, and 5 would be better, and it is advisable to test them occasionally by lowering the water to the blow-off level. Dinner-hour is convenient for this, as the boiler may be filled up, and steam got up again before starting time.

It is specially important that all steam-pipes, feed, and steam connections, and blow-out pipes should not be bound in brickwork or so arranged as not to admit of free movement and expansion, as fractures from pipes being bound fast frequently occur, often disastrously to the attendants. The following figures represent the mode of setting the Lancashire boiler, so as to facilitate cleaning and inspection. The dimensions of flues here given should not, if possible, be made less.

Fig. 93 is a cross-section of the boiler and flues, and Fig. 94 a sectional elevation of the back end of the boiler, the section passing clear of the end plate, as shown in Fig. 95, which is a longitudinal section of boiler and seating; Fig. 96 shows the plan of the brickwork. Figs. 97, 98, and 99 show various blocks for covering flues, &c. At Fig. 100 is given a section of the seating of the single

flued, or Cornish boiler, and details are given of the fireclay cover and seating blocks to a larger scale in isometrical perspective. Fig. 101 shows a general arrangement,

Fig. 93. Cross-section of boiler and seating.

in plan, of boilers, economizer, &c., for a mill of 70,000 or 80,000 spindles.

The method of setting out the flues of both the double

Section in C.D

Fig. 94. Back sectional elevation.

and single flue boilers by the agency of a simple 30 and 60 deg. set square is too plain to require explanation.

Steam engines. In regard to the question of steam

engines, it may be said that fashion largely prevails in this matter. At one time nothing would do but beam-engines, now horizontal engines are almost universally employed.

In the experience of the writer, taking into consideration large numbers of engines, the balance of economy in fuel consumption is on the side of the "McNaughted," or