30 0.74241·48482-2272 2.9696 3·7120'4 4544 5 1968 5·9392 6·6816 30 40 0.7399 1·4798 2 2197 2·9596 3 6995 4·4394 5·1793 5·91926.6591 20 50 0.73731·47462·2119 2·9492 3 6865 4 4238 5 16115 89846 6357 10 60 0.73471 46942 2041 2 9388 3 6735 4·4082 5·1429 5 87766-6123 0 HEIGHTS. 30 0.43730 8746 1.3119 1.749 2.186 2.624 3.061 3.498 3.936 Cos2. 30 0.74240 29 0.74215 0.74190 0.74164 0.74139 0.74113 0.74089 0.74062 22 0.74037 36 0.43810 87631 3144 1.752 2.190 2.629 3.067 3.505 3.943 37 0 43830 87661 31491.753 2.191 2.630 3.068 3.506 3.945 38 0.43840 8769 1.3153 1.754 2.192 2.631 3.069 3.507 3.946 39 0.43860 8772 1·3157 1.754 2.193 2.632 3.070 3.508 3.947 21 0.74011 40 0.43870 87741·3161 1.755 2.193 2.632 3.071 3.509 3.948 20 0.73986 41 0 4388 0·8777 1.31651.755 2.194 42 0.43890-8779 1·3169 1.756 2.633 3.072 3.510 3.949 19 0.73960 2 194 2.633 3.073 3.511 3.950 18 0.73935 43 0.43910-8782 1.31731.756 2.195 2.634 3.074 3.513 3.952 44 0.43920 8785 1 31771.757 2.196 2.635 3.075 3.514 3.953 0.73909 0.73883 45 0.43940-8788 1.3182 1.758 2.197 2.636 3.076 3.515 3.955 15 0.73858 46 0.4395 0.8791 1.31861.758 2.197 2.637 3.077 3.516 3.956 14 51 0.44020 88051-32071-761 2 201 2.641 3.082 3 522 3.962 52 0 44040 8808 1 32121.762 2.202 2.642 3.083 3.523 3.663 53 0.44050 88101·32161.762 2.202 2.643 3.084 3.524 3 964 54 0.44070 8813 1 32211.763 2.203 2.644 3.085 3.525 3966 55 0.44080 88161·32251.763 2.204 2.645 3.086 3.526 3.967 56 0 44090 88191 32291.764 2.204 2.646 3.087 3 527 3 968 57 0.44110 8822 1·32331 764 2 205 2 647 3 088 3.529 3.970 58 0.44120 88251 32371.765 2.206 2.647 3.089 3.530 3 971 59 0.44140-88281 32411.766 2.207 2.648 3.090 3.531 3.972 60 0.44150.8830 1 3245 1.766 2.207 2.649 3.091 3.532 3 973 APPENDIX II continued.-EXPLANATION OF TABLES. The manner of using the Tables is shown in the following example, which is point 5 in the field-book. The generating number (G), is 164, the vertical angle (V), is 77° 32′, and is required to find the horizontal distance (H), and the difference of height (T), between the point and the main station. Look along the line representing 77° 32', in that part of the page dedicated to heights, and in the The nearest angle on that part of the page dedicated to distances is 77° 30' and in the Had this been a line between two main stations it would have been advisable to proceed with more care when finding the distance. The generating number would be multiplied by the sin or cos2 of the vertical angle, which, in the example, is 0.95340; so that 164 x 0.9534 = 156.36. * The Tables are published in full in the Pamphlet form of the Paper, which will be supplied to any member who applies for it.-SEC. INST. C.E. (Paper No. 2393.) "Some Recently Constructed Piers and Harbours on the North and West Coasts of Scotland." By JAMES BARRON, M. Inst. C.E. THE necessity for increased harbour- and pier-accommodation on the north and west coasts of Scotland has been pressing itself on the attention of the Government, and also on landed proprietors whose properties are mainly tenanted by crofters and fishermen. Recent changes, and the depression in agriculture amongst the crofters and cottars of the Highlands and Islands, require that better harbour facilities should be given them, as they are now more than ever dependent for subsistence on the produce of the sea. Proprietors are also realizing the fact that in future they must look more to the sea than to the land for their income. It is therefore of great importance that harbour accommodation be given for shipping fish and agricultural produce rapidly to large centres of population. From the annual returns of the Fishery Board for Scotland, it appears that the number of persons employed at the fishing industry on the north and west coasts is nearly twenty-seven thousand, and there are four thousand six hundred fishing-boats, with nets and gear, representing a capital of £202,000; while the value of the fish caught during the year 1887 amounted to £180,000. Fortunately, the western shores of Scotland, and the east side of the outer Hebrides, are indented with numerous natural harbours, which, for depth of water and accommodation, cannot be surpassed, affording excellent shelter for all classes of vessels, without the aid of breakwaters or piers involving great cost for construction; therefore, what is required are piers of a simple yet substantial character, fit to withstand the shocks to which they are liable from steamers, and erected in sufficient depth of water to permit of vessels approaching them at all states of the tide. The Author thinks that a concise account of a few of these piers and harbours may be of interest. The following is a brief description, along with some particulars of cost, of several structures erected by him : (1) Castle Bay, Barra, Inverness. (2) Loch Boisdale, South Uist, Inverness. (3) Loch Skipport, South Uist, Inverness. (4) Stornoway, Lewis, Ross. (5) Loch Inchard, Sutherland. (6) Loch Eriboll, Sutherland (Plate 6). SITES AND FORM OF PLANS. In selecting the sites for these piers, which are designed to accommodate fishing-vessels and steamers of a large class, the following points were kept in view : Accessibility from the sea, and proximity to existing roads on the land. Sufficient depth of water, that vessels may be water-borne at all states of the tide. Suitability of the ground for holding piles. It is also desirable that the immediately adjoining shore, at both ends of the piers above high-water mark, should be adapted for placing mooring-rings, or palls, in such position that large vessels may conveniently use them for stem and stern moorings, the advantage of this arrangement being that the pier may be made with less frontage than would otherwise be necessary for large vessels to berth at. The form or plan of these piers was determined by the suitability of the ground for holding piles, and the local requirements in the way of accommodation for traffic. Where the necessary depth of water and holding ground was found close to the shore, as at Loch Skipport and Loch Boisdale, the section adopted was more economical than at Loch Inchard, where a considerable amount of building is required in forming an access, the masonry of which is continued to low-water mark, and there joins the timber pier, which is T form on plan. The section adopted at Stornoway forms retaining-walls for ground required for harbour purposes. MATERIALS AND CONSTRUCTION. Although stone of a very rough description is abundant near the sites of all the piers, the expense of quarrying the stones of suitable dimensions, and of building walls on soft ground and in deep water, was found to be much too great; and as there happened to be good holding-ground for piles, it was cheaper to construct the piers of greenheart, it being the only description of timber able to resist the ravages of the teredo. As a matter of economy, pitch-pine was used above high-water mark. It was found that the roads or means of access, when formed with stone, were relatively costly. This arose from the fact that generally no roads existed near the sea-shore. Thus a considerable amount of building in retaining-walls was required, and in some cases rock-cutting was necessary. Briefly, the works were thus executed :-The piers were constructed of Demerara greenheart timber, with the exception of the top beams, joists, flooring or planking, and protecting rail, which were of pitch-pine; the fenders, on the outer faces of the piers, were of American elm. The piles were cut square on the upper end, to prevent the piling-ram from splitting them. The temporary pilerings were of wrought-iron, 3 inches broad by 1 inch thick, fitted and driven on tight. Temporary bolts were put through any pile which showed signs of splitting while being driven. The pileshoes were carefully fitted, with the point of the shoe exactly in the centre of the pile. Temporary bolts, shores and tackle were used, in order that the piles might be driven straight. The best of the piles were selected for the front rows, and adzed on the outer face, that the elm fender-piles might bear evenly on them. The cross-ties and diagonal stays were in one length; all the ties and stays were bedded fair where surfaces met on the piles; and when any pile was out of line, or off the square, a bulkingpiece of greenheart timber was carefully fitted between the timbers before being bolted. The walings were put on in lengths to break bond on the piles. The planking, or roadway of the piers, was in breadths of 10 inches and 12 inches, and fastened with wrought-iron spikes inch in diameter, 8 inches long, with countersunk heads, two spikes in each plank on joist. A clear space, inch wide, was left between each plank, and slips of timber, inch thick, were inserted between them so far as resting on the joists. All the timber was thoroughly coated with pitch-oil and coal-tar. The wrought-iron in the pile-shoes, bolts, spikes, and plate-washers was of a quality equal to N.B. best crown iron. The cast-iron washers were of the toughest grey iron. Annexed is a detailed statement of the cost of Castle Bay Pier, the rates and prices for the others being similar. The piles were driven by a manual piling-engine, with ram weighing 15 cwt. Temporary staging was constructed with the timbers subsequently used in the piers, care being taken to fasten it with chain-lashings and hardwood wedges, to avoid damage by boring for bolt-holes. |