Before the 1760s, ships upon the sea faced great peril from the one calculation they could never make properly: longitude. Latitude is easy, you just take the altitude of the sun at noon or Polaris at night. Longitude, though. That's tricky. It relies on time. Time known at a fixed location, and time known at your location, and the precise difference between the two, with some spherical trigonometry added, draw your longitude line and your latitude line, and where they cross, there's your location. In an era when even the best gravity-pendulum clocks had to be re-wound every week, time was difficult enough to determine with precision; on the rolling deck of a roiling sea, a pendulum clock was useless, and there was yet no time piece more accurate.
So there was no way to calculate one's exact position. Now and then a ship would steer into unforseen shoals, because the captain had thought the rocks were miles east or west, and taken the ship on a course he thought was safe. No such luck. It was a mighty problem, and the main methods of the day, books of navigational advice and charts and the like, were not as precise was what people needed. They needed to be able to know exactly where they were at any given moment, not simply for the sake of avoiding hazards, but to be able to chart a direct course across the sea, and save time thereby. Time was key, in crossing the sea, in the years when ships were small, crews were large, supplies were limited and Scurvy was misunderstood. The usual safe way of crossing took too long as it was. You sailed to a chosen latitude caught a trade wind going your way, and held your ship on the latitude as closely as you could. Two legs of an isoceles triangle. Too long, not precise. God help you if you were trying to reach a small island and missed.
Then someone came up with two great inventions, one forevermore associated with the Age of Sail, the other less remembered now: the Sextant in 1763 and the Marine Chronometer in 1764.
Few remember the Marine Chronometer, yet it was the cutting-edge mechanical technology of its day. The first precision timepiece that could resist being thrown off by the ocean waves. Also very expensive. It demanded great skill in manufacture, leaving it in the hands of individual master clockmakers. They were not mass-produced until the 1940s. Well into the early years of the 1800s they could cost up to a hundred Guineas.
If you were a sailor of the 1840s and going out on a small and poorly-funded ship, or even a moderate and better-funded ship, you were more likely to see a Sextant. Sextants calculate longitude by measuring the angular distance between the moon and another celestial object, then consulting a chart to compare the difference between the measurement with the same measurement done at the Greenwich Meridian, in order to determine the current GMT. And then you can use the same instrument to determine local time, by measuring the precise altitude of the sun or a star, and by this method one may determine distance from GMT. Even better, the instrument can measure one's latitude by calculating the altitude of a the sun at local noon or the Polar Star at night. An ingenious device, and comparatively cheap.
Just be sure your measurements are exact.
Imagine you are in a boat out at sea. A ship, let us say, for it is a respectable vessel, not necessarily one you would have chosen but one that you did not object to when your friends chose it for you. A Barquentine, the Snapdragon, a fast sailing vessel to be sure, which is fortuitous considering that you and your mother, and your friends, Elizabeth and Violet, Mary Anne and Veronica, Charlotte and your dear, dear Esther, the former Lady Asquith, were all eager to be gone from the shores of England sooner rather than later, lest any suspicion fall upon you, slight possibility though it may have been. So Mother picked the first ship she knew of heading towards Barbados whose captain she could trust, which took about a month, in which Esther was not permitted to leave the house, nor appear near an uncurtained window by day, nor descend from the third floor when guests came by, and as she had grown stir-crazy over the month and you were feeling the strain, alleviated only by her nightly attentions, and as your mother had been increasingly polite and curt to you and Esther, it was all to the better that you finally found a reliable passage towards your destination.
Not that your presence is necessarily welcome aboard the Snapdragon, because these sailors are all men, which means -- let us say that they would be distracted by the sight of one woman aboard ship, let alone eight of them, increasingly so on a long journey without the company of...disreputable women. (For goodness sake just call them whores, says Elizabeth. As if you would ever mention such a filthy word.) Sailors are a superstitious lot, you have heard, and they think it's bad luck to have a woman aboard, any woman. Ha! That's not hard to explain. On a vessel that requires constant attention, any distraction from one's work can cause problems, and Esther is rather distracting, no? And your other friends, in many ways. But what will you do? Shut them up in their cabins for the journey?
According to the captain the answer is yes, and no he wouldn't hear any objections, because you and he both know why pretty women on the ship are bad luck. What about pretty men, you say, before realizing what you've said, and the captain gives you an odd look, before he says, the men know what I would do to them if they let that get in the way of their work. Well, fair enough, and maybe Esther's continued sourness is a small price to pay for avoiding ill fortune. And it is also true that on the busy deck of a ship, anyone who's not busy helping sail the ship is an obstacle at best. Even the ship's chief navigator, who looks like he's just standing there, is busy making sure everyone knows where the ship is on the sea.
Unfortunately he winds up being washed overboard in a storm, and they never find him.
There's some bad luck for you, and it would be entirely likely that the crew would have decided to throw you and your companions overboard if you had not stepped in to show that you were just as good at calculating longitude as the lost navigator. Indeed, as soon as the storm abated and the moon shone in the clearing skies, you picked up the Sextant and determined the moon's angular distance from Jupiter, and the altitude of Polaris, and the captain, himself a decent hand with the geometric compass, was able to determine how far off course you had been blown. Then the crew appreciated you, and were willing to see you above decks.
Couldn't be helped, alas, for a lass aboard ship -- and yet when you stand out upon the forecastle and measure the moon and the stars, night by night, there is no untoward handling by the crew, nor even an unkind word. And when Esther at last throws open her cabin door and shows herself out on the deck, under the stars, the crew won't even look at her. Whether they are being respectful, or cold, is not easy to guess, nor will the captain explain.
Perhaps they know what passes between us, says Esther, but surely these men would not understand? But there is little time to speculate when you have to pay careful attention to the angle of the moon. A miseasurement could put your calculations miles east or west of where you are. For her part Esther is willing to listen to you explain the business of parallax and sight reduction as best you can, although she tends to get lost when it comes to the details of trigonometry. It is no matter. She listens. Your mother never listened when you tried to tell her about all this, only told you to stay out there and freeze in the cold night if you pleased. Thank goodness she didn't take the Sextant away from you. It would have been an insult to Father's memory.
When you are done making your precise measurements, you at last pay attention the chill of the ocean's midnight winds, and to how numb your fingers are, until Esther takes your hands in hers, and says, I am sorry for all our miscommunications. And for knowingly going behind your back with...all that I did. I am responsible for our current situation.
You inform her that the blame and the responsibility were shared between all, for while you had the least part of the crime itself, you did accept her into your house, and into your bed, because you had accepted her into your heart to begin with. There was no possibility that you would have accepted a flight from England that did not include you. And here, upon the gently bobbing deck above the gently rolling sea, you feel not simply refreshed but revitalized, vindicated even, for you have put yourself in a place to control an entire ship, to guide it on safe paths across the sea to a far landfall, and so your friends go where you say they will, this time.
Esther gives you a worried look, but says nothing. She kisses you on the cheek, and leads you belowdecks, away from the chill.
Days pass, each the same as the other, and your friends gets more and more stir-crazy shut up in their cabins, until at last the captain accepts a compromise, whereby you all might go up on deck by night, at Middle Watch, in order to learn how a sextant works and how to navigate by the stars. Fair enough. It's cold enough that your friends don't stay above decks too long, save for Charlotte, who pays the greatest attention to your instructions, who learns how to work the sextant more quickly than anyone else, who even asks to watch you and the captain calculate the ship's position. You do not let her watch. That is a private business. Oh, says Charlotte, perhaps you would not want me to tell Lady Asquith. You have to explain to her that it's not that sort of private business, thank you very much. The very idea! No, it's just too complicated for her pretty little -- but she picked up the Sextant well enough, didn't she? You have no good excuse, so you say the captain hates women. Well, says Charlotte, perhaps he does indeed.
A few nights of this and Charlotte is the only one still interested in the sextant. Everyone else takes the night air, watches the serene stars, and retreats belowdecks -- save for Esther, who, each night before you make your measurements, takes your hands in hers, for to warm them against the cold night. Then she goes below, and waits for you to be finished.
Yet tonight you will be out on deck a little later than normal, for Charlotte has things to say to you. She is a smart lass, perhaps not as wise as Veronica nor as clever as Elizabeth, nor as steady with her hands as Mary Anne -- yet observant as any of your friends. And she says, softly and gently, I think I know what you are doing.
You have figured me out, then.
Please do not take my words harshly. I have no desire to tell the others, although this further deception pains my heart. It is has been...too much. Too many secrets, secrets of correspondence and plotting and deliberately mishandled communications, and here we are now on the open sea, flying away from what we knew. I trust that you will guide us safely to shore, somewhere, as I trust you would guide anyone safely to shore. But please. Let this be the last deception.
Please. If you would not break the Lady Asquith's heart, do not break mine. I love you, Katrina. We all do, each in our own way. Remember that.
I will. To the end of my days.
Charlotte leaves you there, standing out on the forecastle, shivering not from the cold, but from what you had thought to do to your friends, weeks ago when the sextant came to your hands. When the ship's course came under your control. Thank God you had checked yourself, before you wrecked everything. A ship that spends more than its expected weeks at sea is one that will see supplies dwindle, and bodies shrivel. Your father described Scurvy once. He only had to describe it once. Just imagine if you had followed your impulse, and taken the ship on a much farther course towards San Andrés, or even, in your wild fancies, Saint Helena, such that you had to cross the dead calm of the Equator, thereby to risk getting stuck, and seeing everyone die by degrees before your eyes. If there had been any survivors of your foolishness, no one who learned the tale would have forgiven you, least of all yourself, and you would have rightly been damned to Hell, as you had made a hell upon the water.
Dawn breaks over the island of Saint Lucia. Where you had chosen to go, after realizing the enormity of your possible transgression. Saint Lucia, close enough to Barbados that it won't be more than a day's journey extra. Close enough to make your point without risking everyone's life. Only the captain and the crew fail to understand, at first. Some of them scorn you for presuming to navigate when you weren't as good as you thought, you stupid girl, you could have got us all killed. The captain laughs, because he's glad you were good enough at navigating that you got everyone as close to Barbados as you could, with only a slight error in the end. Your friends giggle at the thought that the high and mighty mistress of the Sextant had been made to look foolish.
Everyone stops laughing when you tell them the truth -- that you had been making deliberate and minute errors all along the way. That you had knowingly mismeasured the angles of the moon and stars, so that the ship would sail on a course towards Saint Lucia, not Barbados, without the captain ever knowing. Because you wanted to prove that you could be the mistress not only of your own fate, but the fate of many others, in contrast to how your friends had been treating you before.
The captain praises your proven skill with the Sextant, and in the same breath, forbids you from ever setting foot upon his ship again, for you have not simply decieved him, but entangled the lives of his crew in a personal matter they were not privy to. You have not simply taken the ship to Saint Lucia, but taken it on a course whose reefs and shoals you do not know well, thereby to endanger everyone even as you intended not to. He would take your mother wherever she would go -- he tips his hat to her -- but as for you, you broke a sacred trust between a crew and its navigator. Never again. Besides which, as he puts it, the crew wouldn't put up with having you onboard anyway. You were bad luck, in the end. You were the bad luck.
You and your companions are put ashore at St. Lucia, there to wait for passage to Barbados. The Snapdragon is no longer a welcome home on the water.
Esther finds you a welcoming abode at the Soufriér Estate, for she is more adept with French than you, and more charming. Her arms are a welcoming abode of their own, which is fortunate when, after you are settled into your room, and the tension of weeks can be let go, you break down and cry for all that has happened, for all of your folly and selfish recklessness.
One might call it fortunate that your friends remain welcoming, though that would imply it was unexpected. As Veronica puts it, an extra sojourn on Saint Lucia is a fair price for what they did to you.
And yet -- to speak of things in terms of a fair price, this paid for that, transgressions paid with retaliation in equal measure -- to live like that would break Charlotte's heart. You are not satisfied with Veronica's satisfaction. You tell her that you know she loves you, that her reassurance at the beginning of all this, and the great compassion and understanding of all your friends, cannot be forgotten, or left aside lightly. You ask your wisest friend what you might do to atone, how you might repair what damage you have done.
Veronica puts down her embroidery, and, not meeting your gaze, stares out the window and over the noonday fields.
Reassure me that you will not do this again.
Watch for a ship to take us to Barbados, and render your best assistance in all preparations to leave as quickly as possible.
And forgive all, she says. Including yourself. Let the griefs of the past months pass away. Trust your friends, and pledge to us your unwavering honesty among us. Pledge to keep our secrets as we keep yours. To uphold our lives as we uphold yours. To come to our aid when we call, as we come to yours. Swear to this, and we will swear it to you, not simply to set things square between us but to uphold the love we all share. Swear to this, and we will swear it to you, for we must be free of bickering and sin, free from the fear of feebleness that leads us to retaliate in an effort to dominate. Swear to this, not in submission but out of love, as we do for you. That is my charge to you. Do you so swear?
On a clear night lit by the moon, the some of the residents of the Soufriér Estate look out their windows to see all of their guests gathered in a circle near the far Yagrumo grove. The old lady -- did she say she was the mother of all of them? -- is standing in the center. Who knows what they're doing? Looks like some sort of ritual. Or secret pact. Maybe both. Probably not going to say anything about it in the morning. Thank goodness they'll be gone within the week, there's something about all those people that is much too intense. Talking to any one of them is like sitting too close to the fire. Yes, good riddance. They'll do better in Barbados than here.
See what comes of using the sextant wrong? You might as well pay the hundred Guineas for the Chronometer.