472 THE BELL SYSTEM TECHNICAL JOURNAL, APRIL 1951 



to a total of about 60, or more, coils may be installed at a single loading 

 splice. It is expected that a considerable fraction of new installations of 

 subscriber-loop loading may be in terms of splice installations of 651 coils. 

 In occasional instances where large complements are required, and the 

 cable-splicing conditions are not favorable for splice loading, the larger 

 sized 638 coils will be used, potted in conventional types of loading coil 

 cases. This plan avoids the need for developing entirely new, conventional 

 design, cases for the 651 coil. 



Commercial production of the 651 coil and their new splice cases started 

 during 1948. It is expected that the future savings in the cost of new plant 

 (due to the cheaper coils, cases, and installation) will be large relative to 

 the development cost. 



22.8 Summary of Coil Data 



Table XIV gives a summary of electrical and dimensional data on the 

 molybdenum-permalloy core message-circuit coils described in the preceding 

 pages. 



Bibliography {Continued) 



13. Buckner Speed and G. W. Elmen, "Magnetic Properties of Compressed Powdered 



Iron," Trans. A.I.E.E., Vol. XL, p. 596, 1921. 

 24. W. J. Shackelton and I. G. Barber, "Compressed Powdered Permalloy, Manufacture 



and Magnetic Properties," Trans. A.I.E.E. Vol. 47, p. 429, 1928. 



26. V. E. Legg and F. J, Given, "Compressed Powdered Molybdenum — Permalloy for 



High-Quality Inductance Coil," Bell System Technical Journal, Vol. XIX, p. 385, 

 1940. 



27. J. E. Ranges, "Loading The Spiral-4 for War," Bell Lab. Record, Oct. 1946. 



30. S. G. Hale, A. L. Quinlan and J. E. Ranger, "Recent Improvements in Loading Ap- 

 paratus for Telephone Cables," Trans. A.I.E.E., Vol. 67, 1948. 



33. Harvey Fletcher, "Speech and Hearing," D. Van Nostrand Co., N.Y., 1929. 



34. W. H. Martin, "Rating The Transmission Performance of Telephone Circuits," 



B.S.T.J., Vol. X, Jan. 1931. 



35. F. W. McKown and J. W. Emling, "A System of Effective Transmission Data for 



Rating Telephone Circuits," B.S.T.J., Vol. XII, July 1933. 



(to be continued) 



