372 ANNUAL REPOET SMITHSONIAN INSTITUTION, 1913. 



diameter of the armature is 6 meters and the inside diameter is 4.4 

 meters. The radial depth of the laminated structure is 21.5 centi- 

 meters. To permit of overhaul and repair the armature is divided 

 on its horizontal diameter. 



The magnet wheel has a cast-steel hub and arms, and the periphery 

 of the wheel is made up of solid forged steel rings. To these rings 

 cast-steel poles are fixed, the ends of the poles being laminated. The 

 poles are held by dovetails and cotters. 



The field poles are wound with bare annealed copper on edge and 

 all the pole windings are in series. 



The slip rings are of cast steel and carbon brushes are used. The 

 exciter is direct coupled and gives 130 kilowatts at 220 volts. 



Every rotor was tested for mechanical strength by being rotated at 

 1.8 times the normal speed for half an hour; that is, at 450 revolu- 

 tions per minute. 



The bearings are supplied with oil under pressure and the oil is 

 cooled by water coils. 



The other five turbines supplied by J. M. Voith are very similar 

 to the above, with double-runner wheels and two nozzles to each 

 runner. At the official tests all the guarantees were exceeded. 

 Coupled to each of the Voith turbines is a double 8,400 kva., 

 11,000 volts, 50-cycle, three-phase generators made by the Allmanna 

 Svenska Co. Each consists of two seperate armatures and two re- 

 volving fields on a common shaft running on two bearings. By 

 reason of the highly inductive load on the generators, the PF is 

 only 0.6, but with PF= unity, each machine would develop up to an 

 individual capacity of 23,000 electrical horsepower. Each^ double 

 generator weighs 250 tons. 



Figures 1 and 2, plate 3, are from photographs of some of the plant 

 used in the Rjukanfos power house. 



PAULING FURNACE. 



This furnace was invented by Mr. H. Pauling, of Gelsenkirchen, 

 Westphalia, and he took the idea from the well-known horn-break 

 lightning arrester. As installed at Gelsenlrirchen and Innsbruck it 

 consists of two hollow iron electrodes, arranged to form a vee, which 

 at the lowest point is about 4 centimeters across, as shown in figure 5. 

 At this point there are two lighting knives, which can be ap- 

 proached to within a few millimeters and are readily adjustable. 

 The arc strikes across and runs up the diverging electrodes by rea- 

 son of the natural convection currents, and the repelling action of 

 its own magnetic field, but principally because of a blast of heated 

 air from an air-duct immediately below. The arc diverges as it 

 follows the shape of the electrodes, and it attains a length of about 



