A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Places where Slocum mentions navigation-related items
From: Fred Hebard
Date: 2003 Dec 18, 15:07 -0500
From: Fred Hebard
Date: 2003 Dec 18, 15:07 -0500
Herewith is a list of all places I have found in Joshua Slocum's "Sailing Around the World Alone" where he mentions things related to celestial navigation. If anyone can add to the list, please do. I collected these quotations to assist people in evaluating Frank Reed's hypothesis that Slocum took only one lunar, and that he is fibbing when he says he corrected a table used for clearing a lunar sight. Fred Hebard CHAPTER 3: At the meridian altitude of the sun I called aloud, "Eight bells," after the custom on a ship at sea. CHAPTER 4: A meridian altitude and the distance on the patent log, which I always kept towing, told me that she had made a true course throughout the twenty-four hours. CHAPTER 5: On September 10 the Spray passed the island of St. Antonio, the northwesternmost of the Cape Verdes, close aboard. The landfall was wonderfully true, considering that no observations for longitude had been made.... On September 25, in the latitude of 5? N., longitude 26? 30'W., I spoke the ship North Star of London. The great ship was out forty-eight days from Norfolk, Virginia, and was bound for Rio, where we met again about two months later. The Spray was now thirty days from Gibraltar. The Spray's next companion of the voyage was a swordfish that swam alongside, showing its tall fin out of the water, till I made a stir for my harpoon, when it hauled its black flag down and disappeared. September 30, at half-past eleven in the morning, theSpray crossed the equator in longitude 29? 30' W. At noon she was two miles south of the line. CHAPTER 6: On one of the very fine days experienced after leaving Rio, the steamship South Wales spoke the Spray and unsolicited gave the longitude by chronometer as 48? W., "as near as I can make it," the captain said. The Spray, with her tin clock, had exactly the same reckoning. I was feeling at ease in my primitive method of navigation, but it startled me not a little to find my position by account verified by the ship's chronometer. CHAPTER 11: I sailed with a free wind day after day, marking the position of my ship on the chart with considerable precision; but this was done by intuition, I think, more than by slavish calculations. For one whole month my vessel held her course true; I had not, the while, so much as a light in the binnacle. The Southern Cross I saw every night abeam. The sun every morning came up astern; every evening it went down ahead. I wished for no other compass to guide me, for these were true. If I doubted my reckoning after a long time at sea I verified it by reading the clock aloft made by the Great Architect, and it was right. There was no denying that the comical side of the strange life appeared. I awoke, sometimes, to find the sun already shining into my cabin. I heard water rushing by, with only a thin plank between me and the depths, and I said, "How is this?" But it was all right; it was my ship on her course, sailing as no other ship had ever sailed before in the world. The rushing water along her side told me that she was sailing at full speed. I knew that no human hand was at the helm; I knew that all was well with "the hands" forward, and that there was no mutiny on board. The phenomena of ocean meteorology were interesting studies even here in the trade-winds. I observed that about every seven days the wind freshened and drew several points farther than usual from the direction of the pole; that is, it went round from east-southeast to south-southeast, while at the same time a heavy swell rolled up from the southwest. All this indicated that gales were going on in the anti-trades. The wind then hauled day after day as it moderated, till it stood again at the normal point, east-southeast. This is more or less the constant state of the winter trades in latitude 12 degrees S., where I "ran down the longitude" for weeks. The sun, we all know, is the creator of the trade-winds and of the wind system over all the earth. But ocean meteorology is, I think, the most fascinating of all. From Juan Fernandez to the Marquesas I experienced six changes of these great palpitations of sea-winds and of the sea itself, the effect of far-off gales. To know the laws that govern the winds, and to know that you know them, will give you an easy mind on your voyage round the world; otherwise you may tremble at the appearance of every cloud. What is true of this in the trade-winds is much more so in the variables, where changes run more to extremes. To cross the Pacific Ocean, even under the most favorable circumstances, brings you for many days close to nature, and you realize the vastness of the sea. Slowly but surely the mark of my little ship's course on the track-chart reached out on the ocean and across it, while at her utmost speed she marked with her keel still slowly the sea that carried her. On the forty-third day from land,--a long time to be at sea alone,--the sky being beautifully clear and the moon being "in distance" with the sun, I threw up my sextant for sights. I found from the result of three observations, after long wrestling with lunar tables, that her longitude by observation agreed within five miles of that by dead-reckoning. This was wonderful; both, however, might be in error, but somehow I felt confident that both were nearly true, and that in a few hours more I should see land; and so it happened, for then I made the island of Nukahiva, the southernmost of the Marquesas group, clear-cut and lofty. The verified longitude when abreast was somewhere between the two reckonings; this was extraordinary. All navigators will tell you that from one day to another a ship may lose or gain more than five miles in her sailing-account, and again, in the matter of lunars, even expert lunarians are considered as doing clever work when they average within eight miles of the truth. I hope I am making it clear that I do not lay claim to cleverness or to slavish calculations in my reckonings. I think I have already stated that I kept my longitude, at least, mostly by intuition. A rotator log always towed astern, but so much has to be allowed for currents and for drift, which the log never shows, that it is only an approximation, after all, to be corrected by one's own judgment from data of a thousand voyages; and even then the master of the ship, if he be wise, cries out for the lead and the lookout. Unique was my experience in nautical astronomy from the deck of the Spray--so much so that I feel justified in briefly telling it here. The first set of sights, just spoken of, put her many hundred miles west of my reckoning by account. I knew that this could not be correct. In about an hour's time I took another set of observations with the utmost care; the mean result of these was about the same as that of the first set. I asked myself why, with my boasted self-dependence, I had not done at least better than this. Then I went in search of a discrepancy in the tables, and I found it. In the tables I found that the column of figures from which I had got an important logarithm was in error. It was a matter I could prove beyond a doubt, and it made the difference as already stated. The tables being corrected, I sailed on with self-reliance unshaken, and with my tin clock fast asleep. The result of these observations naturally tickled my vanity, for I knew that it was something to stand on a great ship's deck and with two assistants take lunar observations approximately near the truth. As one of the poorest of American sailors, I was proud of the little achievement alone on the sloop, even by chance though it may have been. I was en rapport now with my surroundings, and was carried on a vast stream where I felt the buoyancy of His hand who made all the worlds. I realized the mathematical truth of their motions, so well known that astronomers compile tables of their positions through the years and the days, and the minutes of a day, with such precision that one coming along over the sea even five years later may, by their aid, find the standard time of any given meridian on the earth. To find local time is a simpler matter. The difference between local and standard time is longitude expressed in time--four minutes, we all know, representing one degree. This, briefly, is the principle on which longitude is found independent of chronometers. The work of the lunarian, though seldom practised in these days of chronometers, is beautifully edifying, and there is nothing in the realm of navigation that lifts one's heart up more in adoration. CHAPTER 15: June 26, in the morning, it is a bit squally; later in the day blowing a steady breeze. On the log at noon is 130 miles Subtract correction for slip 10 ,, 120 ,, Add for current 10 ,, 130 ,, Latitude by observation at noon, 10? 25'S. Longitude as per mark on the chart. There wasn't much brain-work in that log, I'm sure. June 27 makes a better showing, when all is told: First of all, to-day, was a flying-fish on deck; fried it in butter. 133 miles on the log. For slip, off, and for current, on, as per guess, about equal ? let it go at that. Latitude by observation at noon, 10? 25' S. For several days now the Spray sailed west on the parallel of 10? 25' S., as true as a hair. If she deviated at all from that, through the day or night, ? and this may have happened, ? she was back, strangely enough, at noon, at the same latitude. But the greatest science was in reckoning the longitude. My tin clock and only timepiece had by this time lost its minute-hand, but after I boiled her she told the hours, and that was near enough on a long stretch. CHAPTER 18 Soon after my arrival at the cape, Mr. Kr?ger's friend Colonel Saunderson, [note]who had arrived from Durban some time before, invited me to Newlands Vineyard, where I met many agreeable people. His Excellency Sir Alfred Milner, the governor, found time to come aboard with a party. The governor, after making a survey of the deck, found a seat on a box in my cabin; Lady Muriel sat on a keg, and Lady Saunderson sat by the skipper at the wheel, while the colonel, with his kodak, away in the dinghy, took snap shots of the sloop and her distinguished visitors. Dr. David Gill, astronomer royal, who was of the party, invited me the next day to the famous Cape Observatory. An hour with Dr. Gill was an hour among the stars. His discoveries in stellar photography are well known. He showed me the great astronomical clock of the observatory, and I showed him the tin clock on the Spray, and we went over the subject of standard time at sea, and how it was found from the deck of the little sloop without the aid of a clock of any kind. CHAPTER 20 ON May 10 there was a great change in the condition of the sea; there could be no doubt of my longitude now, if any had before existed in my mind. Strange and long-forgotten current ripples pattered against the sloop's sides in grateful music; the tune arrested the car, and I sat quietly listening to it while the Spray kept on her course. By these current ripples I was assured that she was now off St. Roque and had struck the current which sweeps around that cape. The trade-winds, we old sailors say, produce this current, which, in its course from this point forward, is governed by the coastline of Brazil, Guiana, Venezuela, and, as some would say, by the Monroe Doctrine. CHAPTER 21 On June 5, 1898, the Spray sailed for a home port, heading first direct for Cape Hatteras. On the 8th of June she passed under the sun from south to north; the sun's declination on that day was 22 degrees 54', and the latitude of the Spray was the same just before noon.