SEE HOW THEY GO
By J. P. W. MALLALIEU, M.P.
VIKINGS, in open boats, crossed the Atlantic hundreds of years before Columbus. How they kept their boats afloat in Atlantic seas or endured the exposure I do not know, even in the mild season that comes in April and May. But that was not the greatest part of the Vikings' feat. Not more than three hundred years ago, it is believed, some unknown seamen crossed the Atlantic in a rowing-boat. Many times since, shipwrecked crews, from Captain Bligh's downwards, have come miraculouily to safety in suicide craft. What is really remarkable about the Viking voyages is that they were made, so far as is known, without the help of guiding instruments. Earlier seamen, like the Greeks, the Phoenicians and the Chinese, had their lode-stone, the lump of magnetic iron which foreran the compass ; they knew, too, about the form of the earth and the relationship of the height of the sun to latitude. Anyway, most of them hugged the coast. But the Vikings launched them- selves into the wide ocean with nothing but the North Star and pure seamanship to guide them.
Few seamen today rely on pure seamanship. True, during the last war I did meet a Merchant Navy skipper who had a contempt for charts and instruments. He used to judge his position along the East Coast by the colour of the water or even, so he said, by its taste. But such men grow rarer as seamanship becomes less of an art and more of an exact science. You can see that development for yourself at the Exhibition of Navigation Through the Ages which the Royal Geographical Society and the newly-formed Institute of Navigation are holding every weekday until January 31st at the Royal Geographical Society's building in London.
One of the oldest exhibits there is the astrolabe. This instrument, originally devised by Hipparchus in 15o B.c., measured altitude. For centuries it was used only on land, and even Chaucer's famous treatise, written in 1387 for his ten-year-old son " little Lewis," barely mentions its use at sea. But the latitude of a place or a ship—that is, its distance from the equator—can be calculated from the height of the sun at noon ; and by the following century seamen had learned to get this priceless information from an -astrolabe. Unfortunately, longitude, or the distance of a ship east or west of a given place, is measured by the daily rotation of the earth, and until a reliable sea-clock could be devised seamen had first to make the required latitude and then steer their ship east or west to its landfall.
This procedure had serious drawbacks, and tremendous efforts were made to find longitude. It was mainly for this end that the Royal Observatory at Greenwich was founded in 1675. In 1714 Parliament passed an Act "for providing a publick reward for such person or persons as shall discover the Longitude." But it was not until 1772 that the Board of Longitude felt justified in paying out this " publick reward "—to John Harrison. A copy of Harrison's clock, made by Kendall, was used by Captain Cook, and can be seen in the exhibition. Cook said of it: " Our error in longitude can never be so great so long as we have so good• a guide as Mr. Kendall's watch." But today Mr. Kendall's watch looks a poor guide to position compared with the wireless and radar devices which are contrasted with it in the exhibition.
During this century there have been greater changes in methods of navigation than at any time in history. Coastal navigation had been made easier by Lord Kelvin's sounding machine in 1872. This allowed a pilot to take soundings at speed and so improved on the old hand-lead-line. Today, Lord Kelvin's device seems as old- fashioned as Mr. Kendall's watch. For one of the most strikingly illustrated instruments in the exhibition is the echo-sounder by which impulses are sent from the ship, hit the sea-bed and are reflected back to give a complete and continuous profile of the bottom with- out effort by man.
Other uses of sound waves, of radio, of radar at sea and in the air are. even more remarkable. I saw a little of them myself during the war. There was a time when the first warning to a ship at sea of approaching aircraft was the sound of engines or the sight of wings. Warning and attack came almost simultaneously. But during the last war, in the Arctic, we knew planes were coming for us when they were miles away. We could watch them coming, even though snow clouds covered the sky and snow-flakes cut visibility. Five minutes before they were due to reach us we could sound-off action stations so that the crews could get themselves out of their, hammocks, into their anti-flash gear and away to their guns and still have time to spare. For our ships carried radar, and when radar impulses hit an object in the sky they were reflected back to the ship and appeared there on a screen as dancing specks of light, specks which grew larger as the object from which they were reflected drew nearer. From these specks a skilled radar operator could tell how many planes there were, how far away they were, how fast they were travelling, whether they were friend or foe. For all I know, he could tell the pilot's name and address and his size in collars. It was frightening to sit in a stuffy cabin, surrounded by icy sea, and watch the approach of death. But that was better than having no chance to drive him away.
Today the principle behind this war-time miracle is used for peaceful purposes of equal wonder. With it you can now not only spot tangible objects, like planes, and so avoid collisions in fogs, but you can even spot far-away clouds. For the impulses are reflected back from the static in the clouds, and so help you to forecast weather. By these impulses you can land a plane in pitch dark or drive great ships through a crowded fairway in dense fog. In the exhibition you can see a model of the Harbour Supervision Radar which covers the entire harbour and approaches at Liverpool and by means of which all objects, moving or still, are plainly visible however bad the visibility may be.
All these new and wonderful devices seem to be doing for the seaman what machines are doing for so many craftsmen—reducing them to unskilled labourers who merely turn knobs. But the Navy, while taking all the new devices and developing them with remark- able enterprise, yet has an aloofness to them, springing from the deep experience of centuries. It knows that machines and devices may fail. Then you must fall back on men. So, in the. age of steam, the Navy still remembers sail ; in the age of echo-sounding, it still remembers the hand-lead-line, and in the age of radar it still remembers the taste of the water near its home ports. I am glad of that. I am glad that the Navy should have all the machines and devices it needs. But I am gladder still that it goes on breeding seamen.
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