IV. MACHINE. —The Merritt Typeteriler.—This machine is designed to be operated by one hand. The type stand upright, and are arranged in a movable trough, which is fitted into another so that i can be moved easily from side to side. In the center is the print ing point. The type are forced through a slot at this point. Which ever type is directly under the slot is forced against the platen, thus making an impression. An index key is attached to the type trough, and the type are so arranged that each one is brought beneath the slot as the indicator is moved opposite the corresponding character. The letters and characters are arranged in front, so that those most fre quently used are nearest. each other. This machine has two shifts, one for capital letters, and the other for numbers and oilier characters. The capitals and characters are arranged on either side of a small letter, so that for one the right shift is required, and for the other the left.. Unlike most of the other machines described, the carriage is not moved by a spring, but is thrust forward automatically.
These are the principal machines now on the market. One of the many requisites of a writing machine is its ability to manifold. Those having type bars are especially well adapted for this purpose, as the leverage is much stronger. In a strong, well-made type-bar machine. 10 or 15 copies can be made very readily, and by using a brass platen and doable carbon, as many as 4o copies are often taken at once.
On account of the numerous parts necessary to every writing machine, all require more or less attention, and for this reason the simplest mechanism and that least liable to get out of order is preferable.
Valve : see Furnaces, Blast, and articles under Engines.
VALVES.—The Locke Ilene:cable-disk Valve is shown in Fig. 1. When the valve is opened enough to admit steam, the soft-metal seat is removed out of the direct line of the steam current, thus bringing the cutting action of the steam upon the cylindrical projection, or plug, instead of on the seat.
The Chapman Gate Valve is shown in Fig. 2. This is a valve specially designed for high steam pressures of 150 to 200 lbs. or more. It has removable bronze seats. The gate in one piece is guided closely in the body of the shell by means of ribs which take all strain. The seats are pressed into their proper positions in the body of the shell, and are held to line by means of a screw gland inserted through the pipe ends.
The Chapman Valve with Automatic Drip is shown in Fig. 3. In many cases it is necessary to drain the water from a pipe, after the supply has been cut off, by closing the main valve. To accomplish this it has heretofore been necessary to put a T into the pipe, with a valve on it, that had to be opened after the main valve was closed. The above-named valve is made with a drip opening, which is shown at the right hand of the cut.
The Spring Valve, used on the Westinghouse steam engine, is shown in Fig. 4. The valve is made a part of the cylinder head of the engine, and has a babbitt face, resting on a seat of cast-iron. The adjustment is accomplished simply by regulating- the pressure on the spring by means of the bolts provided for that purpose. When about to start the engine for the first time, the bolts are slackened sufficiently to allow each water-relief valve to puff steam at each stroke ; they are then gently screwed down, thus compressing the spring, until the puffing stops.
The Ashton Valve is shown in Fig. 5. It is used in connection with steam fire-engines, pumps, stand pipes, and hose in buildings. With it the stream can be shut off at will while the engine is working, and without increasing the pressure or bursting the hose.
The valve case contains a spiral spring, which, by the hand wheel shown, may be adjusted to regulate the pressure. Another form of relief valve is shown in Fig. O. In this valve the nut is stationary, and the screw moves downward to compress the spring and increase the pressure, closing the valve.