DESIGN OF SYSTEM — NORTH ATLANTIC LINK 59 



British-made cable were shipped by truck, following the same precautions, 

 to Idle wild Airport in New York. From there they proceeded by special 

 freight plane — one or two at a time — to London Airport. Here they 

 were again trans-shipped by truck to Erith. 



The repeaters were housed in shipping cases^^ of a very strange shape 

 and considerable size. These cases were provided with max-min thermom- 

 eters and with impactograph devices that would record the maximum 

 acceleration to which the repeaters had been subjected. 



When ship loading time arrived, the cable and its contained repeaters 

 were transported over a system of sheaves from the tanks of the cable 

 manufacturer to the tanks on shipboard. This process offered no particu- 

 lar obstacle so far as the cable itself was concerned, but the requirement 

 against unnecessary bending of the repeater meant that a great deal of 

 special attention had to be given to avoiding unnecessary deviations 

 from a straight run, and to lifting the repeaters around sheaves where 

 the direction of the loading line changed materially. Auxiliary protection 

 was provided on each repeater in the form of angle irons with flexible 

 extensions on each end which served to restrict any bending to the core 

 tube region of the repeater and safely limited the magnitude of the bends 

 in this region. One further precaution was observed — that of energizing 

 the repeaters during the loading process. This accomplished two things. 

 First, it permitted continuous testing; second, it reduced the hazards of 

 possible damage to the electron tubes during loading, as the tungsten 

 heaters are much more ductile when hot and the glassware of the tube 

 is more resistant to shock and vibration. 



SYSTEM PERFORMANCE 



General 



At the time of this writing, the No. 2 cable has just been laid, but the 

 No. 1 cable has had eleven months of successful life under test, a pre- 

 service period of probably greater duration than has been granted to 

 any land system of comparable length and cost. It has been under con- 

 stant observation and test, largely by the people who will operate it 

 when it goes into service. The pre-service measurements have been much 

 more extensive, in quantity and scope, than the routine tests which will 

 be made after the system goes into service. 



Net Loss Tests 



Net Loss versus Frequency 



Results of measurements in June, 1956, on the No. 1 cable are shown 

 in Figs. 12 and 13. The former covers the equalized high-frequency line. 



