E. Dosson.—State of Applied Science in Canterbury. — — 181 
is made for a road, the wind soon lays prostrate the decayed trees, as well 
as all those which may happen to have grown with an outward inclination. 
So many breakages have taken place from this cause, that it would 
appear to be a safer method of construction to erect the telegraph wires in 
the forests at a short distance from the road clearings, merely removing 
enough of the undergrowth to allow of the wires being strained from tree 
to tree. Of course, the lines would be somewhat crooked, and the points of 
support greatly multiplied, but the risk from falling timber would be reduced 
to a minimum. 
The other special cause of breakage lies in the necessity for fixing the 
telegraph poles in many places in the shifting shingle of the river beds. 
The only remedy for this appears to be to sink the foundations of the points 
of support below the limits of the shifting shingle, either by driving in piles 
or by bedding the posts in blocks of concrete, and to diminish their number 
as much as possible. 
By elevating the points of support to such a height that there shall be 
no undue strain, the Provincial Telegraph Manager, Mr. G. Bird, has suc- 
ceeded in erecting with common No. 8 wire, and maintaining without 
accident, spans much larger than those commonly used. 
The following are the largest spans in the Hokitika line :— 
River Porter ae N 1,848 feet. 
Valley of the Seven E cix 21. 
Valley of the Broken River ju 3,498 , 
In the latter instance, the telegraph poles are placed on the cliffs at the 
edge of the valley, which is so*deep that there was no difficulty in giving a 
safe curvature to the wire; and although the action of the wind on this 
immense span is considerable, the wire appears perfectly equal to the strain. 
Although the Hokitika line is carried across two high ranges, the passes 
through which are covered with snow for several months in the year, very 
little inconvenience has been experienced from this cause; but the working 
of the line has been occasionally delayed, in the winter months, by the 
thawing of the frozen snow which has accumulated round the insulators, by 
the heat of the sun, thus causing a current to earth, the insulation being 
restored in the sherióon, as soon as the temperature fell below freezing 
The construction of the western portion of the line to Hokitika was 
attended with many serious difficulties. Upwards of fifty miles were through 
forests inaccessible to horses, and intersected by dangerous rivers; whilst 
the weather in the Alpine ranges was so severe that during one month there 
were only nine days on which it was possible to work. 
