An Encyclopedia of the History of Technology part 57 doc

PART THREE: TRANSPORT 542 for the same purpose, and coastal views and outlines of hills are usually to be found on charts or in sailing directions. Until the late eighteenth century, in fact, specialized marks were rare, and such views often show also church towers, to mention the most obvious. The relative scarcity of proper lights incidentally casts a different angle on the many stories of false lights used by wreckers, for a deep sea seaman would be far more likely to avoid a light than to steer for it. As in other matters, the first lights were established by the ancients, usually in the form of towers upon the top of which a coal or wood fire was kept burning, the Pharos of Alexandria being the best known, while Roman towers survive at Corunna and Dover. Similar methods continued throughout the Middle Ages, the fire usually being in an iron brazier. Most of these lights were on headlands or offshore islands, but their distribution was purely fortuitous, sometimes being the work of a public-spirited local notable, at other times perhaps due to a religious foundation or to a nearby port’s corporation. Passing ships could be charged light dues, so that the profit motive could also bring lights into being. The efficiency of all, however, could be very variable. In England, the Corporation of Trinity House was given powers in the sixteenth century to supervise matters nautical, including the provision of lights. From the eighteenth century a steady improvement began. In the same way that it became possible to build breakwaters to withstand the sea, so lighthouses could be built on outlying rocks—the Eddystone being the classic example, with the first house swept away, the second burned down, and the third, with its interlocked stonework, still extant, though now moved ashore. Better illuminants were found—oil, paraffin, gas—and elaborate systems of mirrors and lenses were brought into use to give better direction and power to the light. The provision of lights was taken over by official bodies devoted to that purpose, resulting in many more and far more reliable lights, placed where they were most needed. In England, Trinity House took on this role, while in Scotland and Ireland, the Commissioners of Northern Lights and the Commissioners of Irish Lights were set up, although harbour authorities also provided more local lights. In Europe and America, government departments usually provided the lights. Lightships were used to provide a permanent light where it was not possible to build a lighthouse, the vessel being moored with heavy cable and anchors. Originally the light would be an oil lamp, and the vessel a dumb craft, unable to move independently, but with the improvement of lighting equipment, lightships came to be provided with generating power to work light and optic, and in some countries, are also self-propelled. The tendency in recent years, however, has been to adopt remote control, and the ships are often replaced by large buoys or small unmanned light floats. Buoys have been used to mark sandbanks and the margins of channels since at least the sixteenth century. They were constructed similarly to casks, PORTS AND SHIPPING 543 or sometimes of a skin over a framework, or might simply be a piece of timber, usually with a small pole and mark on top to make them visible. During the nineteenth century they began to be built of iron and later steel, and their shape could more easily be varied to differentiate one from another. In the late nineteenth century, systems of buoyage were introduced to ensure that one shape and colour had the same meaning everywhere. Lights were increasingly fitted, too, usually using gas, frequently operating continuously, while others had sound signals by whistle, siren or bell. The principal buoy shapes were those known as can, spherical or conical, spar and cagework, with these upper parts mounted on standard ‘hulls’. Daymarks, or ‘beacons’ comprise a variety of poles or small towers with distinguishing marks but no light, mostly in small ports and creeks, although a few are substantial erections such as Walton Tower on the Naze estuary in Essex. The main types of optic used in lights are the catoptric, or reflecting, the dioptric, or refracting, and the catadioptric, which combines the two. Optics are often of considerable size and beauty, and of high efficiency in collecting and concentrating the light from the light source, whether oil or gas as in the past or electricity to-day. Occasionally, one light has provided two beams, where a special danger requires a specific indication. Lights are often shielded so that they only cover specified arcs, and sometimes one of these can be coloured, again to mark a particular danger. For ease of identification, it has long been the practice for adjacent lights to show quite different indications and lights can be flashing (light less than dark) or occulting (light more than dark). Flashes may be in twos, threes or more, while the interval between the signal can be varied. Modern developments include smaller and much more concentrated light sources, often made from plastic materials rather than glass, and an increasing degree of remote control or automatic operation, while, instead of the former ship as a buoy tender, helicopters are used for servicing lights, especially for relieving crews. Most of the important lights also carry a fog signal, usually a reed horn, actuated by compressed air, and occasionally independent fog signals are found. NAVIGATION The early seafarers could only find their way at sea by hard experience in small vessels totally dependent on natural forces, noting winds, currents and tides and using them to best advantage; the instincts developed in such a hard school remain invaluable to seamen and particularly to fishermen. Most early voyagers found their way by hugging the coast, but gradually, by using sun PART THREE: TRANSPORT 544 and stars as well as winds and currents, it became possible to sail across the sea in a generally correct direction. As the celestial system became understood, more use could be made of it, for example, in establishing latitude by observation of the angle of elevation of the sun at noon. The compass was known at least from the thirteenth century, and by the sixteenth the navigator could also use the lead and line to ascertain depth, the log to estimate speed, and a quadrant, cross-staff or back-staff (Davis’s quadrant) to obtain his latitude, while declination tables appeared in the late fifteenth century to assist in the latter. When the sun was not visible, however, no alternative was available, and the navigator could only hope that his estimates of course and speed made correct allowances for currents and leeway. Moreover, the basis for good navigation must be good charts, but these, too suffered from serious defects. The seventeenth and early eighteenth centuries witnessed a slow improvement, rounded off by the invention of Hadley’s reflecting octant in 1731, the basis of the later sextant and a much more accurate instrument for the measurement of angles. One great deficiency remained, the inability to find the longitude at sea. This was overcome to some extent in practice by using latitude sailing, reaching the latitude of the objective well to east or west of it and then sailing along that parallel until the destination was reached. In 1714 the British government offered a reward for the inventor of a reliable method of establishing longitude at sea, and much effort was expended to this end. Eventually, the prize was won by John Harrison, who developed over many years a very accurate clock, or chronometer, so that the difference in time between the meridian of the departure point could be measured against the meridian where the ship actually was. These chronometers were used successfully by Captain Cook, and the method was generally adopted. About the same time, the improvement of astronomy which had result at least in part from the establishment of the Royal Observatory at Greenwich in 1685, with the object of improving navigation, was enabling the production of tables relating to the position and movement of stars (the Nautical Almanac). Using this knowledge it became possible to take sights with a sextant and then calculate (laboriously) the longitude. To do this required more accurate instruments, and these were now available, made of metal (usually brass) to much higher standards and graduated by precision graduating machines. Similar progress was being made in producing more accurate charts, while sailing directions were increasingly published. Thus navigation was at last becoming a precise science, and the end of the eighteenth and the first half of the nineteenth centuries saw a new era of exploration and surveying, in which the Royal Navy took a very prominent part. Knowledge of the depth of water is obviously of primary importance to a navigator. Until well into the twentieth century, sounding could only be done in most ships by the hand lead, a long narrow piece of lead, with a recess in PORTS AND SHIPPING 545 the bottom ‘armed’ with wax to obtain a specimen of the sea bed, attached to a lead line marked in fathoms. The lead was cast ahead in the hope that it would reach the bottom before the ship overran it, and indeed for deep sea soundings the ship would have to be stopped for the laborious running out and heaving in of many fathoms of line. A recording machine was devised by Massey early in the nineteenth century, but this did not avoid the same troubles. In the 1870s Lord Kelvin produced a deep sea machine which could be power worked and which used a special tube filled with a chemical which changed colour in relation to depth. Only the invention of the echo sounder in the 1920s, which timed the return of a noise from the bottom, brought real improvement, and the great advantage that it could maintain a continuous record. Measuring the speed of a ship through the water was, from the mid-sixteenth century, done by the hand log, by timing the running out of a regularly knotted rope for a fixed period, the number of knots passing being termed the speed, hence the ‘knot’ being the unit of speed at sea. It was also possible to use the Dutchman’s log, that is, to time an object passing down the ship’s side between bow and stern. Both methods were obviously approximate, and contributed to the general inexactitude of navigation. In 1802, Massey produced a speed-recording machine similar in principle to his depth recorder, driven by a rotating float towed astern, and this system is still in use in the modern patent log. More recent methods include a recorder driven by a small propeller attached to the hull, while the Chernikeef type uses water pressure on a diaphragm in the hull. Another of the old inexactitudes was compass error, which was little understood until the work of Matthew Flinders early in the nineteenth century on the magnetism of a ship’s hull as well as on deviation and variation. An Admiralty Committee in the 1830s extended this work, and also designed a compass card which was steadier than previous ones. The introduction of iron ships obviously accentuated the effect of hulls upon a compass and necessitated more precautions. Lord Kelvin devised another card in the 1870s, and generally speaking, with regular correction and swinging of the ship, the magnetic compass was reliable and needed little attention. Early in the twentieth century, however, it was found that a gyroscope, left spinning freely, adopts a constant axis and could serve as the basis for a compass, which would give ‘true’ readings direct, while it also could have repeaters driven off the master, and consequently the gyro compass achieved considerable popularity. Since 1945 navigation has changed radically. The wartime refinement of radar and the Decca navigator carried further the use of radio techniques begun before the war with directional position finding. Radar gives the navigator a view of the sea and land in his vicinity, together with the shipping, and can provide accurate bearings and distances, with allowance too in many sets for one’s own ship’s movements, though its use has also produced problems of interpretation. The Decca navigator uses the former DF principle PART THREE: TRANSPORT 546 of two or three directional bearings from shore stations, but these are continuously available, and can be plotted direct on to special charts to give an accurate position at a moment’s notice. Both these developments are concerned principally with waters near land—though radar can be used anywhere—but the methods of inertial and satellite navigation introduced largely for nuclear submarines in the 1960s, provide ships so fitted with instantaneous and reliable positions when far from land. CHARTS AND SAILING DIRECTIONS The earliest charts and their associated texts which give detailed advice to the mariner, sailing directions, are known from classical times, but the earliest surviving ‘sea-maps’ are the so-called portolani, drawn with ink on skins, in mediaeval times. The methods of producing these maps are not certainly known, and, although at a glance many show recognizable outlines of coasts, they are inadequate in detail. There were errors in longitude, while the idea of projection was not understood, nor was the size of the earth known, so that all charts well into the eighteenth century—and even after—embodied errors. In the late sixteenth century Dutch cartographers led, producing printed engraved charts which had wide usage; they were generally known as Waggoners, a corruption of the name of Lucas Waghenaer who first produced them in 1584. The secrecy which many countries maintained with relation to their possessions was to some extent dispelled by these charts, but they were copied extensively and for too long after better work was available. In England, Captain Greenvile Collins produced some more detailed charts of many localities in the 1680s which embodied improved methods of survey. While the Dutch charts certainly included some sailing directions, most prudent mariners also kept their own remarks about the pilotage of ports they had visited. Commercially produced charts held the field for many years. The French navy set up a Hydrographic Office in 1723, the English East India Company appointed Alexander Dalrymple as its hydrographer in 1779, but the British Admiralty did not follow these enlightened leads until 1795, although naval officers had been surveying regularly long before. Dalrymple’s appointment to the Admiralty post was not followed by an extensive output of charts for various reasons, and it was not until 1810 onwards that the Admiralty chart began to establish its reputation. However, from 1815 onwards, the Royal Navy embarked upon a serious effort to chart much of the world, using recent scientific progress to raise the standard very considerably. The long and arduous work of officers such as Smyth, Fitzroy, Owen, King and Denham, together with efficient production and distribution, made these charts more widely available. Meanwhile, Horsbrugh, Dalrymple’s successor, produced a valuable series of sailing directions for the eastern seas. From the 1860s, PORTS AND SHIPPING 547 however, the Admiralty also began its own series of sailing directions or Pilots as they are commonly called, and the resurvey, and revision of both charts and pilots was placed on a regular basis. The British example was followed by many other countries, and for many years most nations have undertaken their own survey work. The work of the surveyors has been much assisted by subsequent developments of new techniques and of instruments such as radar and echo sounders and even aerial survey. Special charts have been found necessary for use with navigational systems such as Decca, and standardized formats have been adopted. PORTS AND HARBOURS The importance of good harbours to economic development needs little emphasis. Not only must ships be able to load and discharge in safety, but for centuries they also needed shelter on their voyages or safe anchorages where they could wait for winds. Until relatively recently, however, man depended on the gifts of geography for these important elements of his society. The earliest craft could readily be beached. When ships became larger, and this was no longer feasible, sheltered places had to be sought where ships could lie peacefully alongside the shore or bank to load or unload. Such sites were mostly on rivers, often, indeed, some way up and not uncommonly at the lowest bridge. Structures in timber, and as early as Roman times in stone, brick or concrete, might be built as quays over which cargo could be worked. Quite extensive works were created in harbours such as Ostia, but much of this knowledge was lost in the Dark Ages, and harbour works remained rudimentary for many centuries. In many cases ships had to lie in the river and load or unload from barges. In such ports, the tide was of much assistance to ships in working up and down the river. London, Antwerp, Rotterdam and Hamburg may be given as examples of this type of port, and countless others may be found. Away from the sandy and low-lying shores of northern Europe, however, reliance was usually placed upon a natural harbour in a bay or arm of the sea, where a point sheltered from wind and sea could be found and the necessary works built. For naval purposes, where less cargo work was done, such harbours were especially popular, as access was easier than with a river. Portsmouth, Brest and Toulon typify such places, while Venice and Marseilles are more commercially oriented examples. Beach cargo working, for coasters, remained in use until the early twentieth century. For shelter during a voyage, or as a safe place in which to await fair winds, the small merchant ship of the sailing era might lie in the lee of an island (the Texel off the coast of Holland, for example) or headland; offshore sandbanks often enclosed sheltered anchorages, such as the Downs or Yarmouth Roads off the east coast of England. PART THREE: TRANSPORT 548 Occasional efforts to build small breakwaters against the full force of the sea usually ended, sooner or later, in failure, with the notable exception of the mole at Genoa in north-west Italy: the Molo Nuovo, built in 1643 survives today. Only during the eighteenth century did engineers develop the ability both to build and to maintain structures against the battering of the sea—Plymouth Breakwater, Whitehaven, Ramsgate and Kingstown Harbours, for example, and these provided amply for shelter as well as improved port facilities. The great increase in trade beginning in the mid-eighteenth century began to make existing ports congested, while the slow increase in the size of ships became much more marked in the first half of the nineteenth century, and rendered the old practice of lying on the bottom at low tide more and more undesirable. Thus efforts were directed towards the provision of wet docks, in which ships could lie quietly in impounded water behind locks and where cargo could be better protected and stored. A few such docks already existed, such as the Howland Dock on the Thames, and some in the naval dockyards and at Liverpool, but from 1800 onwards many more were built, generally by companies set up for the purpose or by municipal authorities, and dock or harbouur management entered a new era far removed from the small-scale efforts of the past. In ports where the tide was less of a problem, similar improvements were nevertheless made to provide open docks with storage and working areas behind the quays. All these works required heavy excavation and building of robust walls, and thus a high level of engineering skill and organization. The advances in port engineering and organization were timely, for the radical changes in ship design, size and purpose throughout the nineteenth century were to set port authorities a hard task to keep abreast. Longer, wider and deeper locks were needed, and the docks to which they led had equally to be enlarged, while the coming of railways required the provision of additional facilities. Steamships, for economic reasons, had to work their cargo far more quickly than in the past, so that improved equipment and methods were needed. To the former warehouses close to the quay were added transit sheds to organize and collect the cargo before loading or after discharge, large storage areas for bulk cargoes such as timber were necessary, while cranes, steam at first and then hydraulic and electric, together with grabs for coal and suction elevators for grain, had to be provided, as well as refrigerated warehouses for meat and later fruit, and tanks for various liquids. The scale of these requirements also increased as individual ships carried more cargo. Thus all ports, to keep up to date, expanded on to new sites; many, of course, dropped out. An era of specialization followed. Many new ports, or greatly expanded ports, were built to meet special needs—railway companies for packet ports or coal shipment ports, mining companies to ship their products—while in some parts of the world, such as India or Africa, completely new ports could be built for areas hitherto ill-served by nature, examples of which are Madras, Port Harcourt and Mombasa (Kilindini). Even in the late Victorian era, passenger traffic was quite PORTS AND SHIPPING 549 ill-served, tenders often having to be used at such important places as London and Liverpool. As the number of passengers in one vessel increased with the size of ships, improvement was needed, and preferably outside the dock so that the ships could leave without reference to tide. Floating landing stages were therefore provided, with railway station and road approach, waiting rooms, customs premises and space for circulation. In more recent years, these quays and other berths have also needed ramps to allow cars and lorries to drive on and off ro-ro ships, with parking areas and buildings to match. Perhaps the first of the specialized cargoes to require separate treatment was oil, which, owing to the risks of fire, was always dealt with at special facilities, usually long jetties with the refinery at the shore end well away from other habitation. This tendency has spread with the increasing use of very large bulk carriers for other cargoes. Coal, iron ore, grain and sugar are now received, as many have long been shipped from special jetties, often adjacent to the works which will use the cargo. The jetties are fitted with modern unloading gear-— grabs, cranes and conveyor systems—and are sometimes of considerable length to reach deep water. Owing to their often exposed positions and the size of the ships using them, the construction of these jetties presents many problems. While containers, the other modern cargo system, are usually handled over quays in less remote situations, they need very large special cranes and much stacking ground, as well as a deep-water berth. Cargo handling The handling of cargo from shore to ship and then again from ship to shore, sometimes with further intermediate handlings such as to a lighter, was always recognized as unsatisfactory owing to its liability to breakage and pilfering, but only for some bulk cargoes was it possible to avoid it. Commodities such as coal or stone could be tipped on board, and, after the introduction of the grab crane, lifted out, while grain and other cargoes of similar characteristics could be handled via pipes and suction pumps. Smaller but more valuable and fragile loads could only be barrowed on the quay, then lifted in small batches by the ship’s gear, in sailing days often by blocks and tackles from the yards, later by derricks rigged on the masts, and then by dock cranes, all using slings and nets. Weights were limited to a tonne or so, although this figure rose as derricks or cranes achieved greater capacity. Beyond this weight, special heavy cranes had to be obtained. By the 1950s, however, both cranes and derricks could handle up to 5 tonnes, and many ships had also a heavy derrick capable of lifting, in some cases, 80 or 100 tonnes, while port authorities also had floating cranes available of even greater capacity. Efforts to avoid handling go back many years, and took two forms, the container and the roll on, roll off vessel. The ro-ro originated with the train PART THREE: TRANSPORT 550 ferry: railway wagons could be shunted on to a special vessel and off at the other side, using ramps or lifts to overcome tidal variations. The first such ferry was across the River Forth in 1849, and it was followed by others, especially in Denmark, while rather similar vessels were introduced for road traffic across rivers, all very short crossings. Longer distance train ferries with seagoing vessels began with the Great Belt crossing in Denmark in 1883, and this was followed by others across the Baltic, in the Great Lakes area and between Japanese islands, and elsewhere. By 1939 the need for similar vessels to convey motorcars was recognized and a few were in service, often on the same routes. During the war, the situation was altered by the construction of large numbers of landing ships and craft for what in essence was a similar purpose, though these relied on bow ramps or doors rather than the stern loading usual in the existing vessels. After the war, converted landing ships or craft were utilized to open new routes, and further new vessels were built for fast cross-channel routes. It was not until the 1960s that a fresh wave of development began based on the conveyance of lorries. New ships were needed with greater headroom and more deck space, as well as loading facilities at both ends. A vast reorientation of trade towards short sea crossings resulted, as well as the decline of many ports. In the late 1970s many deep sea vessels were being provided with ro-ro facilities. The second radical development was the container. This also began with the railways, which, after using small containers to hasten the transfer of baggage from express to cross-channel steamer before 1914, introduced larger ones between the wars to provide a door-to-door service in reply to the competition of road hauliers. These containers were also increasingly used for cargo to Ireland. In the 1950s, a new type of container was developed in America of rectangular shape, allowing them to be easily stacked and to fit closely into suitably fitted ships, and also to be quickly coupled and uncoupled to the crane which transferred them between ship and shore, often direct to lorry or train. These ISO (International Standards Organization) containers have revolutionized the deep sea cargo trade as ro-ro has short sea crossings. Very large and fast ships can carry several hundred such containers, and are able to do the work of several older ships, so much so that the former shipping companies have been compelled to form consortiums to operate the relatively few vessels needed. Other new methods have not made so much impact. Lash and Bacat (Barge Aboard CATamaran) ships are variations on the idea of loading a barge inland and taking it in a seagoing vessel overseas to be distributed by waterway. Dredgers One of the most important aspects of maintaining a port is to keep a constant depth of water. In areas of large tides, silting can be a serious problem, PORTS AND SHIPPING 551 sandbanks can change very considerably and suddenly, and an increase in the size of ships may require the channel to be deepened. For all these purposes, various types of dredger have evolved. In the seventeenth and eighteenth centuries, ballast was dug from river bottoms by a spade-like arrangement and lifted to the surface, and this could be used for dredging if necessary. Such an arrangement could be adapted to steam power, and then evolved into a chain of buckets on a strong rigid frame, the spoil being emptied into chutes and thence into a barge, usually a hopper barge, which could convey it well out to sea and deposit it through bottom doors. Bucket dredgers of this type were the mainstay of the dredging plant of a port. For quaysides and areas which a bucket dredger could not work, a vessel, usually itself a hopper, fitted with grab cranes was used. Suction dredgers were also employed, drawing up silt through a pipe trailing on the bottom. In recent years, the efficiency of this type has greatly improved, and they are now generally used in place of the other types. Other machines such as rockbreakers and piledrivers are also found, usually in harbour construction, while the suction principle is also widely used to obtain gravel and sand for non-nautical purposes. SHIPBUILDING AND DOCKYARDS Shipbuilding in the days of timber ships was a more opportunistic business than it subsequently became with iron and steel. Until the end of wooden shipbuilding, it was a usual practice to build small vessels up to 30m (100ft) long or thereabouts on a convenient site where the ground sloped down to a river, offering a suitable site for the building ways on a firm foundation. Here, using local timber as often as not, the keel could be laid, the frames erected and the hull planked employing only very simple lifting appliances, and with timber scaffolding round the hull, reached by ramps, to allow the shipwrights to work above ground. The hull would be held upright by cradles at various points standing on the ways, and wedged by shores. These would be removed shortly before launch, when the ways would be greased, and the hull on the cradles would slowly slide down to the water. Nearby would be saw pits and perhaps sheds for shaping and preparing the timber, with a steaming kiln to bend it. If no more orders came, the site could be abandoned and revert to nature. Obviously there were also many shipyards which were well-established businesses in important ports, but the essentials were the same, with associated activities nearby, such are ropewalks, rigger’s shops, mastmakers and blacksmiths (for much iron was used). There would also be dry docks, in which ships could be either built or more often, repaired. Such a dock would be excavated in the river bank, lined with timber piles and provided with timber mitre gates closing to form a ‘V’ against the river outside. The ship would be brought in at high tide, and carefully placed with its keel on a row of . winds, the small merchant ship of the sailing era might lie in the lee of an island (the Texel off the coast of Holland, for example) or headland; offshore sandbanks often enclosed sheltered anchorages,. science, and the end of the eighteenth and the first half of the nineteenth centuries saw a new era of exploration and surveying, in which the Royal Navy took a very prominent part. Knowledge of the. waterway. Dredgers One of the most important aspects of maintaining a port is to keep a constant depth of water. In areas of large tides, silting can be a serious problem, PORTS AND SHIPPING 551 sandbanks can change