ELECTRICITY AT THE WORLD'S FAIR. 47 



tlie iron is made in the form of a shallow tray into which the 

 enamel is poured. The wire in the shape of a zigzag forms a fiat 

 coil completely surrounded by this insulating compound. A hot 

 plate suitable for heating a kettle of water or baking griddle cakes 

 is made in the same way, and a grid or frame with gutter-shaped 

 bars filled in with the enamel serves as an oven heater, a sufiicient 

 number of these grids being disposed at various parts of the oven. 

 Operations such as the broiling of steak are performed on a modi- 

 fied form of broiler in which the ordinary wires give place to 

 narrow inverted U-shaped bars. The heating wires are carried 

 through the hollow space of these bars and imbedded in enamel. 

 For the heating of water in special vessels, such as the ordinary 

 kitchen boiler, the vessel is made with a bottom in the form of a 

 hot plate. In all the utensils shown at the exhibition the enamel 

 used is of the ordinary gray variety which requires firing, but an 

 enamel for this purpose has been introduced in England which 

 needs no baking. When it comes to heating either by direct 

 radiation or through the medium of hot air, the form finally 

 adopted is that of a coil of wire wound over a pottery or porce- 

 lain center and partially inclosed in an iron case. For car warm- 

 ing, heaters are placed under the seats, and located so that they 

 can radiate directly into the car, wire guards being placed in 

 front of them to protect the clothing of passengers. Such heaters 

 have been introduced quite extensively into trolley cars, and are 

 said to have been found economical when everything is taken 



Fig. 11. Electric Hot Plate. 



into consideration. They require no attention, and take up no 

 room which would otherwise be occupied by passengers, both 

 items of economic advantage in such a use. Heaters designed 

 to take the place of the hot-air furnace are constructed in the 

 same general manner as those for car use. The plan is to place 

 a large primary heater in the cold-air box of the ordinary fur- 

 nace, and then subsidiary heaters just inside the grating of 

 registers, by means of which additional heat may be obtained 

 when the main heater is insufficient. All classes of apparatus 

 are made to be used with either an alternating or continuous cur- 



