PHYSICS 



(Paper No. 46 was presented at the meeting of 1921. Paper 

 No. 47 was presented at the 1922 meeting.) 



XLVI. A NEW TYPE OF NON-INDUCTIVE RESIS- 

 TANCE WINDING 

 Homer L. Dodge 



From the Physics Laboratory of the University of Oklahoma. 

 A ncAv type of non-inductive winding has been devised which 

 lends itself to the commercial production of resistances in the form 

 of current carrying rheostats for general laboratory use as well as 

 precision standards of high ohmic resistance. The conductor is sup- 

 ported on two parallel rods or cores which may be at any conven- 

 ient distance from each other. It is in this respect that the new 

 winding is superior to the so-called Curtis coils which must be 

 wound upon cores separated l)y only a narrow slit. The winding 

 follows the formula: 



.... o.xoxxoxoo.xuxxoxooxoxxoxo .... 

 in which "o" indicates that the conductor is carried from one sup- 

 port to tile other without crossing through the space between the 

 supports while "x" indicates that the conductor is carried across 

 the space between the supports when passed from one to the 

 other. .'\ny group of eight operations produces one "unit" of the 

 winding". 



A rough sketch, made according to the formula, is useful in 

 shov/ing the characteristics of the winding. It will be. found that 

 every part of the conductor is closely adjacent to a similarly placed 

 part carrying the current in the opposite direction. Thus a very 

 small coefficient is secured. The capacity is also sm.all as there is 

 but one layer of wire and the potential difference between adjacent 

 strands is small. For the same reason it is possible to use oxide- 

 covered wire for rheostats. 



XLVII. THE SIMPLE RIGIDITY OF A DRAWN TUNG- 

 STEN WIRE AT INCANDESCENT 

 TEMPERATURES 

 V/illiam Schriever 



From the Physics Laboratory of the University of Oklahoma. 

 The simple rigidity of a 10-mil drawn tungsten wire was de- 

 termined at temperatures between 1000° and 2000° K. A static 

 method was employed. By applying the same torque to both a short 



