CHAPTER XXVII.
MISCELLANEOUS USES OF ELECTRICITY.
171. The Many Uses to which the electric current is put are almost numberless. New uses are being found for it every day. Some of the common applications are given below.
172. Automatic Electric Program Clocks, Fig. 252, are largely used in all sorts of establishments, schools, etc., for ringing bells at certain stated periods. The lower dial shown has many contact-points that can be inserted to correspond to given times. As this revolves, the circuits are closed, one after the other, and it may be so set that bells will be rung in different parts of the house every five minutes, if desired.
| Fig. 252. | Fig. 253. |
173. Call Boxes are used to send in calls of various kinds to central stations. Fig. 253 shows one form. The number of different calls provided includes messenger, carrier, coupé, express wagon, doctor, laborer, police, fire, together with three more, which may be made special to suit the convenience of the individual customer. The instruments are provided with apparatus for receiving a return signal, the object of which is to notify the subscriber that his call has been received and is having attention.
| Fig. 254. | Fig. 255. |
Fig. 254 shows another form of call box, the handle being moved around to the call desired. As it springs back to the original position, an interrupted current passes through the box to the central station, causing a bell to tap a certain number of times, giving the call and location of the box.
174. Electric Gas-Lighters. Fig. 255 shows a ratchet burner. The first pull of the chain turns on the gas through a four-way gas-cock, governed by a ratchet-wheel and pawl. The issuing gas is lighted by a wipe-spark at the tip of the burner. Alternate pulls shut off the gas. As the lever brings the attached wire A, in contact with the wire B, a bright spark passes, which ignites the gas, the burner being joined with a battery and induction or spark coil.
Automatic burners are used when it is desired to light gas at a distance from the push-button. Fig. 256 shows one form. Two electromagnets are shown, one being generally joined to a white push-button for turning on the gas and lighting it, the other being joined to a black button which turns off the gas when it is pressed. The armatures of the magnets work the gas-valve. Sparks ignite the gas, as explained above.