FOREIGN LINES AND CONNECTIONS 81 



the proposed crossing site, showing the contour of the shore on each side for 500 

 ft. from the water-line, and a profile of the body of water along the proposed line 

 of crossing should accompany each report. 



Submarine telephone cables may be roughly divided into three classes: 



(1) Rubber-covered copper wire protected by two or more heavy servings of jute 

 impregnated with waterproofing compound. 



(2) Rubber-covered and taped copper conductor, inclosed in a heavy lead sheath 

 either bare or juted. 



(3) Rubber-covered, taped, and juted copper conductor inclosed in an armouring 

 sheath of galvanized-iron wires, left bare or juted. 



There are no standard specifications for conductors of the third 1 class for forest 

 protection telephone lines and none are contemplated by the Forestry Branch, as the 

 use of such lines on the reserves will be comparatively small. The cost of the heavy 

 cables is so great that each case must be studied separately so that the lowest-priced 

 cable that will give satisfactory service may be specified. 



Of the cables above described, the first is the least expensive; the last, the most. 

 Rubber-covered wires that will give satisfactory service under unusually favourable 

 conditions may be secured as low as $50 per mile. Heavily- armoured cables, proof 

 against injury in all but the most adlverse sites, will cost from $500 per mile, up. 

 Intermediate types will range between these figures in cost. 



In waters having any perceptible current, either the ordinary current in a 

 stream, OP tidal or wind currents in other bodies of water, nothing but an armoured 

 cable is likely to give satisfactory service. The nature of the currents, the contour 

 of the crossing, and the character of the 'bottom will determine the weight of armour 

 required. 



In still waters, such as large lakes or ponds, either heavily insulated wire or 

 lead-sheathed wire may be used. Insulated wire without a lead! sheath should only 

 be used in perfectly still water where there is a mud or sand bottom in which the 

 wire will embed itself. Such waters will usually be shallow and have a fairly 

 regular profile. If used for navigation or log-driving or rafting, the chances of the 

 wire being disturbed by such operations must be fully considered. In nearly all 

 cases, where the approach to the shore is on a gradual, shelving bottom, a heavy pile 

 or tripod properly weighted should be set in the water at a sufficient distance from 

 'the shore to permit of the wire being brought to the surface in a water depth of 

 ft. to 8 ft. and carried to shore by an overhead span. The probable effect of ice on 

 this construction must be considered. Such spans should! not, as a rule, be over 

 ^ mile to mile in length and should always be tested for some months before 

 permanent shore structures are erected. If they fail, replace with a lead-sheathed 

 cable, making the shore connection as above, and use the insulated wire for station 

 installations or for emergency or temporary land lines. 



For spans of over \ mile in still water with a mud, sand, gravel, or rock bottom, 

 where excessive irregularities of profile do not occur, the most satisfactory cable will be 

 a lead-sheathed one. On a gravel or rock bottom it should have an outer jute covering. 

 The shore approach may be made as previously described, but in most cases it will be 

 found more satisfactory to splice on to each end of the span a short length of armoured 

 cable with which to make the shore approach from a depth of about 15 ft. Landings 

 may be made with armoured cable where the rock slopes off very steeply into deep 

 water; or the cable may be brought ashore on a sand or mud bottom sunk in a trench 

 and, if possible, protected by a light covering of rocks or gravel and a few stakes or 

 piles to warn off boats. However, if logs drift loose in the lake, or if the landing place 

 is exposed to a heavy surf, an overhead landing is preferable. 



Always set up at each end of a submarine cable crossing a large sign warning 

 navigators against anchoring over the cable. 



The actual laying of a submarine cable is very simple. The reel on which it comes 

 wound should be mounted on the stern of a boat of suitable size, or, if none is 



7*9211- % 



