EOUTE SELECTION AND CABLE LAYING 319 



to outweigh all other considerations and left only one problem, namely, 

 shielding from interference. 



Up to this time shore ends of submarine cables used by the Post Office 

 were shielded for about a quarter of a mile from shore by a lead sheath 

 insulated from the return tapes of the coaxial by a polyethylene barrier. 

 Experience indicated that such shielding might not be adequate over a 

 long distance on land. The question was resolved by the addition of iron 

 shielding tapes and a plastic jacket to standard submarine cable. The 

 structure is described elsewhere.^ 



Through the use of this robust, wire armored cable and two steel 

 housed submarine repeaters, no limitations from the noise pickup angle 

 were placed on the detailed route selection for the overland section. The 

 first thought was to try to proceed directly across country from Claren- 

 ville to Pipers Hole River, saving at least 10 miles over a route which 

 followed the road, and on which advantage might be taken of quite long 

 water stretches into which the cable could be dropped. Black River Pond, 

 for instance, is 4| miles long. This proposal was abandoned after surveys, 

 because of the very rocky nature of the country and difficulty of access 

 both for construction and any subsequent maintenance, and it was 

 decided to follow the general course of the roads. 



It was possible to avoid trenching in the rocky, precipitous cliff coun- 

 try from Clarenville to Adeytown by laying about 6 miles of cable in 

 the water of Northwest Arm. Similar considerations dictated the choice 

 of two miles of cable in the sea across Southwest Arm. Thence the route 

 followed the road, at a distance ranging from 250 yards to more than a 

 mile, as far as Placentia Bay, taking advantage of the larger ponds where 

 possible to avoid trenching. 



Reaching the 800 foot high ground beyond the Pipers Hole River from 

 the north of Black River proved quite difficult. Here the road is carved 

 out of the foot of the cliffs as far as Swift Current and the country behind 

 is solid rock. Plans exist for a hydro-electric project involving dams in 

 Pipers Hole River just north of the road crossing and it is naturally not 

 desirable to bury a cable in such a locality. The river estuary itself pass- 

 ing by Swift Current presents only a narrow 6 foot deep navigable chan- 

 nel at low water but it was decided that this could be used for some 6 

 miles by employing a barge and a shallow draft tug for the laying. 



A suitable route out of the basin up through wooded gorges to the 

 top took about a week of very hard going to locate. Thereafter all was 

 plain sailing taking advantage of ponds such as Long Pond (4 miles) 

 and Sock Pond (3 miles) until the route arrived within G miles of Ter- 

 renceville. 



