252 



SCIENCE. 



[Vol. XIII. No. 322 



substitute for the chamois-leather now used for these and for 

 analogous purposes. Being, moreover, of a woven texture, and 

 absorbent, it is more healthy for use in garments than chamois- 

 leather, and does not require to be perforated. Unlike leather, 

 also, which gets stiff after washing, this improved material so pro- 

 duced is capable of being repeatedly washed without stiffening, and 

 is found to retain its softness perpetually." 



THE ELECTRIC RAILWAY IN ST. JOSEPH, MO. 



One of the successful electric street-railways in the country is that 

 in operation upon the Wyatt Park Company's line at St. Joseph, Mo., 

 a view of which we give in this issue. This line at St. Joseph was 

 the first one in the country to practically demonstrate the success- 

 ful operation of an electric railway in a snow-storm. In the early 



A NEW FORM OF SELF INDUCTION AND 



REGULATING COIL. 



In the operation of electric lighting and other apparatus in which 

 an alternating current is employed, it is frequently desirable to vary 

 the current or electro-motive force through considerable range. 

 With direct or continuous currents, a variable rheostat is usually 

 employed for such purpose, and, where saving of energy is not an 

 object, might be used also with alternating currents. But with 

 such currents it is possible, by employing self-induction or induc- 

 tive resistance in place of pure resistance, to secure such variations 

 without much loss of energy, because the action of self-induction 

 is really only a storing-up and giving-back of energy consequent 

 on a displacement of phase of induced alternating impulses from 

 the phase of impressed or supplied impulses. This is what is 



SPRAGUE ELECTRIC RAILWAY AT ST. JOSEPH, MO. 



part of this winter a blizzard from the Western prairies struck St. 

 Joseph with all its force, and covered the streets in that city to the 

 depth of from six inches to one foot, in many places drifting badly. 

 The telephone, telegraph, and electric-light wires were borne 

 down by the snow in all parts of the city. In spite of this general 

 blockade, the electric railway ran uninterruptedly, and the cars 

 ploughed their way through the heavy drifts on the line without 

 trouble or stoppage, and without any aid from snow-ploughs. 



The grades on the Wyatt Park Railway are in some points on the 

 road as high as nine per cent ; and the cars reach a speed of fifteen 

 to eighteen miles an hour in the outside and suburban districts, 

 reducing to a lower rate of speed when operating within the city. 



St. Joseph, Mo., already has two street-railways operating by 

 electricity on the Sprague system, and a great many manufacturing 

 industries are kept in operation by the same power by means of 

 stationary electric motors operated from the regular railway circuit. 

 It is said that the two other street-railways in St. Joseph will soon 

 be in operation upon the electric system, so that the horse shall be 

 supplanted entirely for car service in that city. 



meant by " lagging of phase," and it is an effect of self-induction 

 or inductive resistance. Any wire capable of producing magnet- 

 ism is a self-inductive resistance to such currents. A coil wound 

 on an iron-wire core or bundle is a good example ; and, if the wire 

 bundle be a ring core or closed magnetic circuit, its effects per 

 unit of length of wire will be enormously intensified. 



Hitherto the usual plan of constructing a variable inductive re- 

 sistance has been to provide a hollow coil with a movable iron-wire 

 core in its axis, so that the centres of coil and core could be made 

 coincident for maximum effect. This arrangement for a given 

 effectiveness is cumbrous and unnecessarily large, inasmuch as it 

 employs only an open magnetic circuit, and not a closed one ; and, 

 even though the core be entirely removed from the coil, the self- 

 induction is not neutralized, because of the numerous turns of wire 

 in the coil itself. Besides, the true resistance of the wire as such 

 is considerable. 



With a view of obviating these defects, and securing the other 

 advantages of compactness and ease of manipulation, the apparatus 

 to be described was devised. 



