Table of Contents / Explorers
Magellan Strait
Pacific Ocean
Spice Islands


            The Friendly Islands, the Dangerous Archipelago, the Unfortunate Isles, Cape Desire, Land of Fire, Islands of Disappointment, Land of the Holy Ghost, Islands of Thieves—such place-names given to Pacific geographic features by European explorers sound like they were lifted from a children’s board game where the object was to navigate around dangerous or hot spots in order to reach safe havens. But confronting more than twenty-five thousand islands, and without very accurate means of establishing locations, Pacific navigation in the Age of Exploration was often more pinball-like: ships rebounding from island to island to known port, searching for wind and water and fresh food and welcoming natives, and often renaming places that others had previously “found.” A good map was only half of the solution; the other was having the means of locating one’s ship on that map.

[Click on the images below for high-resolution versions.]

Two developments in scientific marine instruments in the last half of the eighteenth century led directly to much more accurate mapping, hence more reliable navigation and more systematic exploration: the sextant (John Bird, 1757) for determining latitude and the marine chronometer (John Harrison, 1761) for determining longitude. (Latitude and longitude are the X and Y of mapping, the coordinates of a place’s “address.”) The sextant followed in an evolving line of instruments (quadrant, astrolabe, cross-staff, back-staff, octant) designed over the centuries to obtain one’s latitude, or angular distance north or south of the earth’s equator. English instrument maker Bird improved on the octant by expanding its scale range from one-eighth of a circle (45°) to one-sixth (60°), hence the sextant’s name. It was truly a “point-and-shoot” device that divided the field of view into two: one for the horizon and one for the celestial object. By moving the index arm of the instrument until both images were aligned—the celestial object just touching the horizon—one then could determine the angle separating them by reading the pointer on the scale of the arc. The ship’s movement on the sea had no effect, because both objects moved together.
            A sextant was accurate to about one-fifth of a minute. Given that a minute is one-sixtieth of a degree, or about one nautical mile, the instrument’s accuracy translates to latitudinal readings that are within approximately 0.2 nautical miles. Measurements were taken at noon using the sun or at night using Polaris, the North Star, which indicates true north and does not move, for it is aligned with Earth’s rotation. (With sextant readings of the sun, the tilting of the Earth’s axis, the sun’s angle of rays at the equator or its declination, has to be taken into account. This angle changes throughout the year, from 0 to 23.5 degrees, as the earth revolves around the sun. Depending on being north or south of the Equator, one would have to add or subtract this declination to obtain an accurate latitude reading. In Cook’s time, there were published declination tables for each day of the year. Sextant readings of Polaris to determine latitude in the Northern Hemisphere were more straightforward: if Polaris is 10° above the horizon, one’s latitude is 10° N.) It is no coincidence that Captain James Cook, the man considered to be the best navigator of his time, had the advantage of using sextants on his three historic voyages.

Early instruments for navigation. Plate XX from N. Bion ‘s The Construction and Principal Uses of Mathematical Instruments. Tr. from the French of M. Bion. To Which Are Added The Construction and Uses of Such Instruments as Are Omitted by M. Bion; Particularly of Those Invented or Improved by the English. By Edmund Stone. . . . (London, 1723). [Rare Books Division]


  1. Compass card
  2. Compass needle
  3. Complete compass
  4. Azimuth compass
  5. Sea-astrolabe
  6. Brass ring or circle
  7. Quadrant
  8. Fore-staff or cross-staff
  9. Illustrations of cross-staff use
  10. [more]
  11. [more]
  12.  English quadrant or back-staff
  13. Semi-circle

Early nineteenth-century octant, manufactured by the London firm of Spencer, Browning & Co., formerly Spencer, Browning, & Rust (“SBR” engraved on scale). Note the two mirrors, two-hole peep sight, three sun shading lenses, brass index arm, and ivory scale arc and vernier. [Photograph courtesy of John Blazejewski]

Note, however, that latitudes define circles around Earth, not points on them; for that one also requires longitude, the angular distance east or west of some predetermined prime meridian, which circles around the two poles of the earth and passes through a given place. But there is no natural line for longitude that is equivalent to latitude’s equator. Until international agreement made Greenwich, England, the prime meridian in 1884, maps reflected longitudes based on a number of different reference points, such as London or Paris. Because Earth revolves through its 360° in twenty-four hours, each hour represents a longitudinal difference of 15°, or roughly sixty nautical miles (sixty-nine statute miles). If it is noon in New York City when it is 9 a.m. in Los Angeles, California, then the angular difference between the two cities must be 45°, and a map would show a distance of about 3,100 miles (69 × 45) between them. However, until the development of the marine chronometer, a ship’s captain in the Pacific had no idea what time it was anywhere else unless he was adept at the lunar method* of determining longitude.
            In 1714, the British Parliament passed the Longitude Act, offering a prize of £20,000 (worth several million today) to anyone who could solve the longitude problem. John Harrison (1693–1776), son of an English carpenter, began tackling the problem in the 1730s, creating a series of increasingly smaller, portable, and more accurate timepieces, called H1, H2, H3, H4, and H5. A viable marine chronometer had to be reliable and accurate; it had to resist corrosion from the salt air and remain unaffected by fluctuating temperature and humidity conditions and the rocking movements of a ship on the sea. In 1761, H4, which was about the size of a soup plate, surpassed the Longitude Act’s accuracy requirements, showing a loss of only five seconds during a sea trial aboard a ship sailing from England to Jamaica. Parliament, however, wanted more testing and offered only partial payment to Harrison. In fact, the official reward was never paid to anyone, though Harrison did receive several additional amounts through 1773. Owing to his more than forty years of work on chronometers, he is generally credited with solving the longitude problem. On his second and third voyages, Captain Cook was fortunate to use K1, a version of Harrison’s H4 that was made by London watchmaker Larcum Kendall.** With these two tools—sextant and chronometer—Cook would literally change the map of the world.

* The lunar method was a complicated technique requiring measuring the angle between the moon and another celestial object like the sun or a star, and then consulting published tables of angles to learn the Greenwich, England, time of the observation. One then would have to find the current local time to make the comparison needed for determining longitude—and how to judge that accurately?

** On his first voyage, Cook determined longitude by the lunar method

Just as important as instruments, however, were the scientific methodologies that were employed on these nautical expeditions. Central to the scientific revolution already under way by the seventeenth century was the Royal Society of London for the Improvement of Natural Knowledge, the 1660s creation of twelve natural philosophers, including Robert Boyle (1627–1691), discoverer of “Boyle’s Law” that showed the inverse relationship between the pressure and volume of a gas; John Wilkins (1614–1672), founder of the metric system; and Sir Christopher Wren (1632–1723), architect of St. Paul’s Cathedral. The members met weekly to view experiments and discuss science. The Society’s motto, nullius in verba, interpreted today as “nothing in words,” emphasized from the beginning its interest in experiment and proof, following the inductive methodology popularized by Sir Francis Bacon (1561–1626) as a superior alternative to Aristotelian deductive reasoning. It is the oldest such society still in existence.
            For English seamen “bound for far voyages,” the Royal Society took an active role in developing guidelines for exploration. These were more widely distributed in its publication Philosophical Transactions, Giving Some Accompt of the Present Undertakings, Studies, and Labours of the Ingenious in Many Considerable Parts of the World, which began in 1665. The Society asked Laurence Rooke (1622–1662), a mathematician and philosopher and one of its founding members, “to think upon and set down some Directions for Sea-men going into the East & West Indies” to aid their observations of natural phenomena; these would be recorded in journals and copies delivered to the Society and the Admiralty upon the sailors’ return. Rooke completed his task but died before the Society’s journal was born; his “Directions for Sea-men, bound for far Voyages,”* however, appeared in its eighth issue (January 8, 1666). In hindsight, Rooke’s ideas seem fairly routine and commonsensical (“who wouldn’t do that sort of thing?”)—but after all, he was a mathematician, not a mariner—yet until then there had been no “standard” approach. Even if he had set the bar fairly low, the fundamental, scientific process had begun. Here are his suggestions or rules for useful nautical exploration, in his own words (his italics):

  1. To observe the Declination of the Compass, or its Variation from the Meridian of the place, frequently; marking withal, the Latitude and Longitude of the place, wherever such Observation is made, as exactly as may be, and setting down the Method, by which they made them.
  2. To carry Dipping Needles with them, and observe the inclination of the Needle in a like manner.**
  3. To remark carefully the Ebbings and Flowings of the Seas, in as many places as they can, together with all the Accidents, Ordinary and Extraordinary, of the Tides. . . .
  4. To make Plotts and Draughts of prospect of Coasts, Promontories, Islands and Ports, marking the Bearings and Distances, as near they can.
  5. To sound and marke the Depths of Coasts and Ports, and such other places near the shoar, as they shall think fit.
  6. To take notice of the Nature of the Ground at the bottom of the Sea, in all Soundings, whether it be Clay, Sand, Rock, &c.
  7. To keep a register of all changes of Wind and Weather at all hours, by night and by day, shewing the point the Wind blows from, whether strong or weak. . . .
  8. To observe and record all Extraordinary Meteors, Lightnings, Thunders, Ignes fatui, Comets, &c. marking still the places and times of their appearing, continuance, &c.
  9. To carry with them good Scales, and Glasse-Violls of a pint or so, with very narrow mouths, which are to be fill’d with Sea-water in different degrees of Latitude, as often as they please, and the weight of the Vial full of water taken exactly at every time, and recorded, marking withal the degree of Latitude, and the day of the month: And that as well as water near the Top; as at a greater Depth.

Latitude, longitude, currents, winds/weather, bearings, soundings—these are the basic data elements of any good ship’s logbook, even today. By asking seamen to record them and share the information with others on the return of a voyage, Rooke was advocating a greater openness in sea-going exploration.

* Philosophical Transactions, vol. 1 (1665–1666), pp. 140–43. Reprint edition (Amsterdam: Nieuwkoop, 1963–1964).

** These needles measure the magnetic dip or angle made by a compass needle with the horizon at any point on Earth’s surface. The dip is downward (or positive) in the northern hemisphere, upward (or negative) in the southern.

In an “Appendix to the Directions for Seamen bound for far Voyages,” published in the Society’s ninth issue (February 12, 1666)* , two useful instruments contrived by Robert Hooke (1635–1703), the curator of experiments of the Royal Society, were described and illustrated. The first showed “how to sound depths of the Sea without a line” (Hooke’s fig. 1, his emphasis), thus aiding the implementation of Rooke’s fifth suggestion. A light wooden ball (A), sealed with varnish or pitch to prevent its absorption of water, is carried down in the water by a heavy weight, such as a piece of lead or stone (D). The latter hangs from a springing wire (C) that is attached to the ball. When the heavy stone hits the bottom, the wire compresses, releasing the ball, which then ascends to the surface. The observer measures the number of seconds or minutes the ball stays under water and, by using tables, can estimate the depth from which it has risen. According to the article, tests of such a device in the Thames River proved its utility.
            A second invention allowed a seaman to obtain a sample of water from any depth (as in Rooke’s ninth suggestion). Using the instrument would determine if seawater was less salty at or near the bottom. The Dutch traveler and historian Jan Huygen van Linschoten (1563–1611) had claimed in an account of his East and West Indian travels that in the Persian Gulf “[t]hey fetch water by the Island of Barein [Bahrain], in the sea, from under the salt water, with instruments foure or five fathome deepe, which is verie good and excellent sweete water, as good as any fountaine water.”** Many voyages had difficulty finding fresh water on foreign islands, so having a device that could bring such water up from the ocean would be a definite advantage. The instrument was essentially a rectangular box (Hooke’s fig. 2) with a hinged top and bottom (E). As it was lowered in water (C), the hinged pieces swung up like open valves, allowing water to pass through. However, when the box or bucket was pulled steadily up (G), the hinges closed, locking in a sample of the water at the depth where the bucket’s direction had changed. The article encouraged seamen to use the instrument to test Linschoten’s claim. Thus, by Hooke or Rooke, as it were, the English were determined to have some ground rules and tools for successful exploration. (Whether or not Hooke’s inventions were ever tested on an expedition, they reveal some of the practical concerns of explorers of the period.)

* Philosophical Transactions, vol. 1 (1665–1666), pp. 147–49. Reprint edition (Amsterdam: Nieuwkoop, 1963–1964).

** Jan Huygen van Linschoten, Iohn Huighen van Linschoten, His Discours of Voyages into ye Easte & West Indies . . . (London, 1598), p. 16.

Instruments designed for seamen “bound for far voyages” by Royal Society curator of experiments Robert Hooke. From unnumbered page preceding p. 147 of vol. 1 (1665–1666) in the reprint edition of Philosophical Transactions (Amsterdam: Nieuwkoop, 1963–1964). [General Library Collection]

At the end of the seventeenth century, before the New Holland expedition of Englishman William Dampier, an expanded set of expedition instructions was published independently by another Royal Society member, covering the kinds of samples of flora and fauna that explorers should bring back with them. These were John Woodward’s “Brief Instructions for Making Observations in All Parts of the World: As Also for Collecting, Preserving and Sending over Natural Things. Being an Attempt to settle an Universal Correspondence for the Advancement of Knowledge both Natural and Civil.”* Woodward was a geologist and physician; Society president Robert Southwell had encouraged him to write this pamphlet. The twenty-page publication has six sections:

  1. At Sea
  2. Upon the Sea-shores
  3. At Land
  4. An Appendix relating to the Natives of Guinea, Monomotapa, and other the less known parts of Africa: of the East, and West Indies: Tartary, Greenland, or any other remote, and uncivilized, or Pagan Countries
  5. Directions for the Collecting, Preserving, and Sending over Natural things, from Foreign Countries
  6. A List of such Instruments, and other things, as may be serviceable to those Persons who make Observations, and Collections, of Natural Things

In section I, Woodward improves on Rooke’s suggestions by asking, for example, for observations of tides, birds at sea, and floating debris; in II, he gives instructions for divers of pearl and coral, and for seekers of amber. In the “Land” section (III), Woodward’s background in geology becomes apparent: he suggests that explorers note the sorts of soils they encounter; investigate caves, grottos, and mines for minerals; and examine the earth and rocks for seashells, fish bones, and other marine bodies. Furthermore, tree types, diseases and their seasons, and vegetable and animal production should be identified where possible. Woodward seems prophetic here in encouraging the study of fossil evidence and the life cycles of disease, which would prove useful even in Europe.
            In section IV, dealing with people living in remote countries, Woodward’s interests combine those of both physical and cultural anthropology: he believes that physical features are important (body shapes, colors, and adornments), but he also wants explorers to observe the natives’ temperaments, their virtues and vices (from a Christian standpoint?), their ideas of creation and time, their laws and government. Section V, the longest part, concerns the specimens to be brought back. Woodward explains what to choose and how many of each type to preserve, noting that all places and seasons are worth the observing and collecting efforts of expeditions. He describes how to pack up teeth, minerals, and fossil-shells in boxes, trunks, or barrels; to dry and preserve plants in paper; and to keep the more “rare, curious, and tender” entrails of beasts, fish, fowl, and serpents in jars filled with rum, brandy, or wine.
            Aware of the numerous tasks he has been delegating to future voyagers, Woodward strikes a more reasonable attitude in his conclusion:

‘[T]is not expected that any one single Person will have leisure to attend to so many things, and therefore ’tis only requested that he make such Observations and Collections, more or less, as may be best suitable to his Convenience, and to his Business. If there be never so few Observations made, or things collected, yet even they will be very gratefully received. [p. 16]

In addition to the more obvious scientific instruments—weatherglass (devised by the same Robert Hooke mentioned above), thermometer, quadrant—that one would need on an expedition, Woodward added chisels and hammers to his list of recommendations; the geologist recognized the usefulness of the tools of his trade for examining minerals and rocks.

* “Drawn up at the request of a person of honour and presented to the Royal Society” (London: Printed for Richard Wilkin, 1696).

A third Royal Society initiative was made directly by Society president James Douglas, Earl of Morton (1702–1768)*, to Captain James Cook as he was setting out on his first voyage in 1768: “Hints offered to the consideration of Captain Cooke, Mr. Bankes, Doctor Solander and other Gentlemen who go upon the Expedition on Board the Endeavour.”** These principles related more to the proper handling of social interactions between crew and indigenous peoples, anticipating problems and seeking to preempt their development:

            To exercise the utmost patience and forbearance with respect to the Natives of the several Lands where the Ship may touch.
            To check the petulance of the Sailors, and restrain the wanton use of Fire Arms.
            To have it still in view that sheding the blood of those people is a crime of the highest nature:—They are human creatures, the work of the same omnipotent Author, equally under his care with the most polished European; perhaps being less offensive, more entitled to his favor.
            They are the natural, and in the strictest sense of the word, the legal possessors of the several Regions they inhabit.
            No European Nation has a right to occupy any part of their country, or settle among them without their voluntary consent.
            Conquest over such people can give no just title; because they could never be the Agressors. . . .
            There are many ways to convince them of the Superiority of Europeans, without slaying any of these poor people. . . .
            If the Ship should fortunately discover any part of a well inhabited Continent, many new subjects in Natural History might be imported, and usefull branches of Commerce set on foot, which in process of time might prove highly beneficial to Brittain. . . .

Lord Morton then suggests that the expedition note the natural dispositions of the people; their progress in science and astronomy; their methods of communicating their thoughts over distance; the character of their persons (features, complexion, dress, habitations, food, weapons); and their religion, morals, order, government, distinctions of power, police, and the natural productions of the country, including animals, vegetables, and minerals. (Much of this echoes Woodward’s instructions of the previous century.) In effect, Cook had been given both a rough moral and practical guide.

* Morton died two months after Cook sailed.

** Chiswick, August 10, 1768. In The Journals of Captain James Cook (London, 2003), vol. 1, pp. 514–19.

In the narratives of his voyages, Cook would try to comply with these Royal Society “instructions” and “hints” by providing great detail, often illustrated, of all aspects of the lives of the peoples he encountered. In his coverage of Tahiti, for example, one chapter is subtitled “A particular Description of the Island; its Produce and Inhabitants; their Dress, Habitations, Food, domestic Life and Amusements.” Writing about Tahitian tools and “manufactured” materials, Cook devotes several pages describing how the women make tapa cloth from the bark of the paper mulberry tree:

Their principal manufacture is their cloth, in the making and dying of which I think there are some particulars which may instruct even the artificers of Great Britain, and for that reason my description will be more minute. . . . The shape of this instrument [bottom instrument shown in the plate] is not unlike a square razor strop, only that its handle is longer, and each of its four sides or faces is marked, lengthways, with small grooves, or furrows, of different degrees of fineness . . . . They beat it first with the coarsest side of this mallet, keeping time like our smiths; it spreads very fast under the strokes, chiefly however in the breadth, and the grooves in the mallet mark it with the appearance of threads; it is successively beaten with the other sides, last with the finest, and is then fit for use. [pp. 210-12]

Cook was the first explorer to bring this native cloth, still popular with today’s tourists of Pacific islands, to the attention of Europe. From volume 2 of Hawkesworth’s An Account of the Voyages Undertaken by the Order of His Present Majesty for Making Discoveries in the Southern Hemisphere . . . (London, 1773) [Rare Books Division].

It was not too difficult a leap for the Royal Society to make from Woodward’s seventeenth-century “Everyman’s” practical guide to its eighteenth-century notion that expeditions should take real specialists along for the journey, such as artists, botanists, and physicians. In fact, as the sponsor of Cook’s first voyage, the Royal Society insisted on the inclusion of Joseph Banks (1743–1820), the English naturalist and botanist. (Indeed, this tradition is continued even on today’s cruise ships, where subject specialists, such as ornithologists, marine biologists, and historians provide lectures as informative entertainment to the tourist passengers.)
            Thus, within a hundred years (1666–1768), the Royal Society had developed progressively more robust practices and humane principles for the benefit of government, science, and yet-to-be-discovered subjects. It would remain to be seen how these things operated in the field—the true test of any new idea—culminating in the three landmark voyages of Cook in the 1760s and 1770s, 250 years after the first European expedition (Ferdinand Magellan) dared enter into the vastness of the Pacific Ocean.

Table of Contents / Explorers
Magellan Strait
Pacific Ocean
Spice Islands