PERSONAL EXHIBIT AT THE WORLD’S FAIR.
483
increasing the starting torque and was found very effective inthis connection. Figs. 306 and 308 show a favorite constructionof armature; the iron body is made up of two sets of discs cutaway and placed at right angles to each other, the interstices be-ing wound with coils. The one shown in Fig. 308 is providedwith an additional groove on each of the projections formed bythe discs, for the purpose of increasing the starting torque by awire wound in these projections. Fig. 307 is a form of armaturesimilarly constructed, but with four independent coils wound uponthe four projections. This armature was used to reduce thespeed of the motor with reference to that of the generator. Fig.300 is still another armature with a great number of independentcircuits closed upon themselves, so that all the dead points onthe armature are done away with, and the armature has a largestarting torque. Fig. 303 is another type of armature for a four-pole motor but with coils wound upon a smooth surface. Anumber of these armatures have hollow shafts, as they have beenused in many ways. Figs. 309 and 310 represent armatures towhich either alternating or direct current was conveyed bymeans of sliding rings. Fig. 309 consists of a soft iron bodywith a single coil wound around it, the ends of the coil beingconnected to two sliding rings to which, usually, direct currentwas conveyed. The armature shown in Fig. 310 has three insu-lated rings on a shaft and was used in connection with two orthree phase circuits.
All these models shown represent early work, and the en-larged engravings are made from photographs taken early in1888. There is a great number of other models which were ex-hibited, but which are not brought out sharply in the engraving,Fig. 297. For example at m is a model of a motor comprisingan armature witli a hollow shaft wound with two or three coils fortwo or three-phase circuits; the armature was arranged to be sta-tionary and the generating circuits were connected directly tothe generator. Around the armature is arranged to rotate onits shaft a casting forming six closed circuits. On the outsidethis casting was turned smooth and the belt was placed on it fordriving with any desired appliance. This also is a very earlymodel.
On the left side of the table there are seen a large variety ofmodels, n, o, p, etc., with fields of various shapes. Each of thesemodels involves some distinct idea and they all represent gradual