ELECTRIC TELEGRAPH TO PORT CHALMERS AND THE HEADS.

Otago Daily Times, Issue 47, 9 January 1862, Page 3

ELECTRIC TELEGRAPH TO PORT CHALMERS AND THE HEADS.

The following report from Mr. Mount fort, •who has surveyed the route of the line of telegraph, has been placed at our disposal for publication : — In accordance with your verbal instructions I proceeded to survey nnd examine a line from Duneilin to the Heads via Port Chalmers, for the purpose of carrying a Telegraph Wire. In the accompanying tracing I have marked in a red line the proposed route, crossing from Port Chalmers over the islands to the Portobello side, and from thence to the Heads. Regarding the first part of the lino, it can be carried by George-street, Dunedin, to the Water of Lcith, whero the District Road to Port Chalmers commences ; and as far as section 56, North-East Valley, the road is level, but the timber required for the posts for that part of the line, would require to bo brought from some of the timbered land adjoining. .The distance of this part of the line is 3£ miles. Prom section 56 the gronud begins to rise with a steep ascent, and continues to do so along the whole line, up to section 86, a ■ distance of l-£ miles. The country on either side of the roadis heavily timbered, and there is abundance of manuka and neapan, either of which timber is well adapted, from its durability, for the purpose of posts for carrying the wire. From section 86 the road begins rapidly to descend, and continues to do so as far as Sawyer's Bay—the distance of the descent is 1J miles. Prom section 19, in Sawyer's Bay, the road coritiuues near the Coast, until it reaches George-street, Port Chalmers. The posts for this part of the line would require to be brought from a short distance, as the bush has been cleared along the road line, but there is abundance in the neighbourhood. Upon the line reaching George-street, Port Chalmers, I propose that a short line should deviate from the main route, so as to connect it with the Customhouse, as shown in the tracing. The main line then continues from the last point along Wickliffe Terrace until it reaches Bernicia-strcet, up which street is continues until it reaahes the highland opposite the first island. This last point is shown upon the plan of triangulation of the islands point 4. I will now call your attention to the accompanying plan of the triangulation and sectional elevation of the islands. At point 4, on the high land, in the Peninsula of Port Chalmers, there is an elevation from low water level of 120J feet, and at point 3 on the first island, there is an elevation of 178J feet. The distance between the two points is 17 chains. It will require a mast on either side of the channel to support the wire, (as shown in the sectional elevation). The elevation of point 2 on the larger island, is 202 feet; the points 2 and 3 are the main points to be considered, as between, these points is the channel for vessels of any size, and the wire would require to be kept up at an elevation of about 150 feet above the water to be safe, ns I have been informed upon good authority, that some of the light American barques carry masts of about 120 feet in height. The actual distance between points 2 and 3, is 25 chains, while the width of the channel is only 6£ chains, so that to enable vessels of the large class to pass under, it will require on either side of the channel, well secured on the land, a mast of about 150 feet in height ; the foot of each mast should be about 30 feet above the water level, so as to allow for the deflection of the wire, which will be considerable in that distance. Regarding the third channel between the larger island and the Portobello side, there is not much difficulty, as .there are rocks in the channel which could be used to secure posts for carrying the wire; (the distance from-the island to the mainland is ten chains). This is a dangerous passage to anything but small boats, therefore the elevation of the: wire would not be of so much consideration. After crossing the last channel, the line runs along the south side of the peninsula, and crosses it by means of a road line between sections 10 and 11, (see tracing), after which it crosses 'he Portobello Bay in a straight line, as the b;i" in that part is nearly dry at low water ; on reaching the other side of the bay at section 28, it continues along the coast until there is a cross road line between sections 14 and 15, which road line will carry it through to the Native Reserve, after which. it will require to keep inland, as shown upon the tracing. It descends just above the Maori kaik, where the line again takes the beach, continuing so until it reaches Hobart Town Point, where it requires to cross it in the direction indicated in the tracing, as the beach at this point i:> rocky, and precipitous. After leaving this point, it proceeds on high land across the narrow neck between the Native and Government Reserves to the Signal-staff at the Heads, the terminus of the wire. With regard to timber for the latter part of the line, it can be had on the spot as far as the end of Portobello Bay, after which it will require to be brought for the purpose in boats, as there is abundance of timber in the neighbouring bays. . ■ ; I will now take the opportunity of making a few observations which have suggested themselves to me during my survey. The first and very important one is, that as the line passes over the hill to Port Chalmers through very heavily timbered laud, great danger will constantly arise to the wire from the falling of branches of trees, and sometimes of trees themselves, across the wire. It would be even liable if the wire weie carried along the centre of the road, as at the present time ; there are trees tying across the road, having been blown down by the wind ; but as the wire would require to be carried along the side of the road, it would be in great danger from settlers clearing their land on the road frontage. The next difficulty arising is that of crossing the islands at so great an elevation. From information which I have gleaned from practical men, I have reason to believe that the masts and stays required for carrying the wire would not cost less than frbfh ,£SOO to £600,—a considerable item for so short a distance of the line, besides the difficulty of carrying the wire across such a space, and to obtain such a strain upon the wire as to prevent too great a deflection, and consequently coming in contact with the higher masts of vessels. I have merely made these remarks, Gentlemen, with a view of calling your attention to them, and, if you think fit, for the obtaining the advice of some practical man on the subject. I will now suggest a route to your notice, which from personal observation of the same, I believe to be attended with fewer difficulties than the former. I have worked this line on the tracing in green,and propose that it should tun down tlie west side of the harbour, at a sufficient distance from the shore to prevent any accident from trees, and crossing the projecting peninsulas by means of road lines, it then, after crossing Sawyers' Bay, continues along George-street, Port Chalmers, in a straight line with astation at the Custom House; then proceeding along the west, side of the lower harbour, until it arrives at the Sand Hills, at the end of the surveyed sections, when it proceeds across the Sand Hills and sand flat opposite to Hobart Town Point, which I would propose to cross by means of a short cable the whole distance for the cable being only about twenty chains. The whole distance of this route is fifteen miles, while that of the former is rather over seventeen miles. The latter route after crossing over to Hobart Town Point proceeds to the Heads by , the same route as the former line. . CHARLES W. MOUNTFORT, Surveyor. Dunedin, Dec. 18th, 18G1.