In order to avoid the inconvenience and expense of replacing the fire-brick arch, what is known as the “Jauriet water-table” has been extensively used on some roads. This is the invention of Mr. C. F. Jauriet and is represented in fig. 215, and consists of a flat “table,” _B C_, formed of two boiler plates placed about 4¹⁄₂ in. apart, with the space between filled with water. The two plates are stayed with ordinary stay-bolts in the same way as the sides of the fire-box. The form of the water-table is similar to that of the fire-brick, excepting that it is not arched, this form not being necessary, as the plates are riveted to the sides of the fire-box. Air is admitted above the fire both by hollow stay-bolts and holes in the door, as shown at _A_. Tubes, _f_, are put into the front and lower portion of the water-table to allow the ashes and cinders, which would otherwise be deposited above, to fall down on the grates. [Illustration: Fig. 216.] When air is admitted at the furnace door of an ordinary fire-box, it is very apt to rush directly into the tubes without mingling with the gases. It was found by some of the firemen on English railroads that by placing a shovel over the top of the furnace door, the current of air which entered could thus be deflected downward, and in this way smoke could be almost entirely prevented. This led to the adoption of a hood or deflector, _A_, fig. 216, which is made of sheet iron and is placed over the fire-box door and is arranged with a lever, _B_, so that it can be raised in order to be out of the way when coal is thrown on the fire. It is suspended from a hook, _C_, from which it can easily be detached and taken out for repairs. This is frequently necessary, as the intense heat of the fire-box burns away the sheet iron of which it is made very rapidly. It can be made of old boiler plate, so that the expense of renewal is very slight. When this plan is used, a double sliding door, shown in fig. 217, is commonly used with it. These doors are opened by the levers _f d_; and _e g_, which are all connected together. With these sliding doors the opening for the admission of air can easily be regulated, and the opening through which the lever, _B_, is attached to the deflector, _A_, can be arranged more conveniently than with a swinging door. This plan has been employed by the Rogers Locomotive Works. [Illustration: Fig. 217. Scale ³⁄₈ in. = 1 foot.]