In these days of water-tube boilers, with their rapid steaming qualities and their small steam spaces, as compared with the cylindrical boilers, coal economy and efficiency are greatly augmented by, if not due entirely to, systematic firing.
During the official trial of the U. S. S. Chattanooga, an excellent opportunity presented itself to observe the results of intelligent and systematic firing on the part of the fire-room force of that ship.
To regulate the time interval the engineer officer of the Chattanooga, Lieutenant A. T. Graham, U. S. N., got up a device very similar to that shown in Figs. 1 and 2 of this article. Wishing the Galveston to make as good a record on her coming trial as the Chattanooga, I took the liberty of copying as closely as possible Lieutenant Graham's device and installed it on the Galveston.
The simplicity with which one can be made and installed aboard any ship in the Navy is my only reason for putting this before the service, for I claim no originality, the idea being an old one and there being, I believe, several devices of this nature on the market.
All the material required in the construction can easily be had aboard ship; one fire-room clock can usually be spared for this purpose.
Fig. 1 shows the box containing the lights (six in this case) with the bunting removed from one side. The lights are wired to the six binding posts at the top and front of the box and to one common negative post at the rear. The side pieces are grooved to receive the wires under the keyless lamp sockets. The clock is shown with the face exposed and the board carrying the contact points thrown back. The wire over the upper right-hand corner of this board is the feed wire secured to the clock casing by one of the hinge-screws.
The contact points (6o) are so adjusted that the minute-hind touches them in succession, causing one light after another to burn, since the current passes through the clock and each contact point when the minute-hand closes the circuit. Points 1, 7, 13, etc., 2, 8, 14, etc., etc., are wired together as shown in Fig. 2, and each series of points is connected to its proper binding post on the lamp-box.
Attached to the common feed-wire leading to the clock case and to the common negative post on the lamp-box are two wires attached to an ordinary lamp-socket plug (shown at the side of the lamp-box), for connecting the whole with the dynamo circuit of the ship.
In this case 16 c. p. lamps were used, but much smaller ones will do, allowing a smaller and neater box being used.
The board is secured to the clock as shown and no other insulation than the wood itself is used.
In Fig. 2 the light-box is shown with bunting on and the lights numbered and also the wiring of the board.
There being sixty contact points, the interval between the first flash of the lights in succession will be one minute, provided the clock is keeping proper time, hence by properly numbering the furnace doors any firing interval in multiples of one minute may be obtained.
The Galveston having six Babcock and Wilcox boilers, with one furnace and three doors to each, it is necessary in order to fire three of the eighteen doors at once to use six lights, making the interval between firing any one door six minutes and any one furnace two minutes.
The method of numbering the furnace doors of the Chattanooga's boilers is fully described in the last issue of the "Journal of the American Society of Naval Engineers."
The whole device, clock and all, is mounted in the passageway between boilers C and D, and is visible from both firerooms.
The water-tender being relieved, to a certain extent, of looking out for the time interval in firing has more time to devote to keeping the water-level constant, another thing of prime importance, and also to the method of firing. The firemen are instructed to fire only when the light of the corresponding furnace shows up and in this way excellent results are obtained.
So far the clock used has shown no signs of being affected by the current passing through it, except that the minute-hand is gradually fusing through at the point of contact with the brass pins.
Since constructing the above many improvements have suggested themselves to me, as they will no doubt to others who read this article.