726 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 19vSl 



require stub cables, for office rack-installations, for submarine cables, and 

 for buried, insulated wire. The splice-loading designs include individual 

 cardboard containers for small exchange area (Fig. 21) and toll cable coils 

 (Fig. 20), and baked varnish impregnated spindle-assemblies of coils for 

 coaxial cable order-wire circuits, and for small exchange area cables (Fig. 22) . 



Case Sizes and Shapes 



Where involved, the case size and shape limitations have generally been 

 imposed by underground cable installation conditions. The circular tops of 



Fig. 23 — Office type loading coil case for installation on office mounting 



plates. Designed for potting molybdenum-permalloy core program 



circuit loading coils. 



the cast iron cases and the rectangular tops of the welded steel cases had to 

 be small enough to permit lowering the cases through the circular manhole 

 openings in the loading manholes and loading vaults. In the early applica- 

 tions of loading, 26 and 27-inch manhole openings were very common; later 

 on, 30-inch openings became standard for loading manholes. In recent years, 

 in redesigning the large, thick-steel cases that required 30-inch manhole 

 openings for their installation, the superseding thin-steel designs were pro 

 portioned to permit installation in line manholes having 27-inch openings. 

 The case bodies of the cast iron cases were approximately circular in cross- 

 section with scallop-shaped contours corresponding to the compartments 

 in which the coil spindle-assemblies were mounted. These ranged from 3 to 

 7 in number. In the rectangular cross-section, welded steel designs, there 



