Thomas Yocum
The Gulf Stream by John Elliott Pillsbury is one of the classic works of modern oceanography. This work was first published as Appendix 10 of the Superintendent of the United States Coast and Geodetic Survey Report for 1890. The first three chapters of this work were devoted to the history of the exploration and study of the Gulf Stream from the time of the early European explorers to the year 1884. Pillsbury, a naval officer, undertook his famous studies from the Coast and Geodetic Survey Steamer BLAKE at that time and the remainder of The Gulf Stream was devoted to discussions of his instruments, methods and results. The first three chapters are reproduced in an abridged version here as Pillsbury was as meticulous in his historical studies as he was in his scientific work. These chapters provide a historical framework for the beginnings of modern physical oceanography as it includes the thoughts of 16th and 17th Century explorers and "cosmographers," Benjamin Franklin's work on the Gulf Stream, and the studies of numerous late 18th and early 19th Century scientists.
This work all preceded the first systematic oceanographic studies conducted by any nation, the Gulf Stream studies begun by the United States Coast Survey in 1844. Guided by Alexander Dallas Bache, naval officers commanding Coast Survey vessels led these early oceanographic expeditions. Bache, the second superintendent of the United States Coast Survey, set the formula for modern integrated oceanographic cruises by directing that physical oceanography, geological oceanography, and biological oceanography be incorporated into these pioneering cruises. Over the next 40 years, the Coast Survey continued pursuing knowledge of this great oceanic current. The efforts of the Coast Survey and the affiliated naval personnel associated with the early Gulf Stream studies did much to help lead the United States into the modern realm of oceanography.
Introduction
Geography, the science that gives to us a knowledge of the earth's surface, is divided into two branches: first, all that pertains to the configuration, usually called geography, and second, everything relating to the natural forces acting thereon, called physical geography. These subjects are interlaced with the study of nearly every branch of human knowledge tending toward the good of the race in its struggle toward improvement. At first the pursuit of wealth by the discovery of new lands and peoples, brought about a study of the configuration of the surface, but little by little it was seen that the study also of the physical forces assisted toward this end and to the ease and comfort of mankind at large.
The Sun without doubt is the greatest factor in the support of terrestrial life, but this intense heat is tempered and governed by the elements, air and water, without which life as at present constituted on our globe would be unsupportable. The total area of the earth's surface is about 200,000,000 square miles, and of this only about one-fourth is land. The mean elevation of the land above the sea is less than 2,500 feet, while the mean depth of the ocean is probably about 12,000 feet. The total volume of the land above the sea level, therefore, is only about one twentieth of the volume of the ocean.
The surface of the ground quickly becomes heated by the direct rays of the sun, but it also quickly radiates its heat into the air, producing an aerial current. The surface of the water, on the other hand, absorbing the sun's heat, rapidly communicates it to the adjoining stratum, and, radiation from its surface being comparatively slow, its currents transfer the heat so acquired to distant points. The tempering influence on the climate is the wind, taking the heat and moisture from this heated water and transferring it to the land. It is argued most forcibly that such a stupendous change in the climatology of the world as existed during the glacial period was caused by the precession of the equinoxes and the change in the eccentricity of the earth's orbit effecting an alteration in the great heat distributors, the ocean currents.
To commerce and navigation the study of these currents is of the utmost value. The length of the voyage is shortened, and the chance of safety to vessel, cargo, and lives is increased. A strong wind against a current produces a dangerous sea, and, by a knowledge of the laws of the water's flow, a vessel, by a trifling change of course, may escape the danger.
Zoological geography may consider them as highways which unite the zones of the ocean, and consequently cause the dissemination of species, and at the same time by the intensely progressive attenuation of salt and the temperature of these waters this highway facilitates the evolution of species. It is thus that the currents enter into the question so important to origins, monogenism, or polygenism.
Anthropology, for example, holds them responsible for the solution of the great problem, that of human migrations, which spread even to the distant archipelagos the different varieties of the race man, at the time when there was scarcely a discernible difference between man and beast, and he had at his disposal only rudimentary means for struggling against the brute forces of nature.
Botany and zoology ought to be interested in our researches, for the conditions of organic life in all its bearings are governed by these currents either warm or cold, which give to subterranean regions a veritable climate; and it is perhaps owing to certain disturbances which have taken place in the volume, direction, and temperature of these currents that the almost entire disappearance of several kinds of migratory fish is attributed, as, for example, that of the sardines, which formerly lined the coasts of France in countless numbers.
It concerns geology also, for the oceans receive a deposit, the organic and mineral detritus which the winds and waves bring to it, the stones which the glaciers wrest from the polar regions and which the icebergs carry to the temperate regions. The sea currents charge themselves with distributing all these minerals according to certain laws, and in this manner collections are formed which in later times convulsions of the earth bring to light.
Paleontology itself ought to be interested in our researches, for is it not evident that the rivers, drifting dead bodies across the continents, deposit them on sand banks far from their habitat to become the fossils of the future?
There is another reason for studying these currents which will ultimately have the most beneficial influence on mankind. It is now known that the currents vary through certain forces acting upon them, by periodic changes, entirely according to law, and again through apparently erratic forces. Probably every motion of these vast bodies is absolutely governed by laws which can be ascertained. The moisture and varying temperature of the land depends largely upon the positions of these currents in the ocean, and it is thought that when we know the laws of the latter we will, with the aid of meteorology, be able to say to the farmers hundreds of miles distant from the sea, "you will have an abnormal amount of rain during next summer," or "the winter will be cold and clear," and by these predictions they can plant a crop to suit the circumstance or provide an unusual amount of food for their stock. We will be able to say to the mariner, at such time the current will be so much an hour in such a direction, and the percentage of error will be but trifling. From a study of these great forces, then, we derive our greatest benefits, and any amount of well-directed effort to gain a complete mastery of their laws will revert directly to the good of the human race.
In the Atlantic Ocean the currents are probably more pronounced than in either the Pacific or Indian Oceans. Without entering upon a discussion at this point as to the causes of ocean flow or of any particular current, a brief description of the main streams will not be out of place, for they are all connected more or less intimately with our own Gulf Stream. The equatorial current is usually described as being a broad band of water moving slowly across the Atlantic in the tropics. The portion situated south of the equator is divided into two parts upon meeting the resistance of Cape St. Roque, the eastern salient point of the South American coast. One branch turns to the southward toward the Antarctic, and the other is forced to the westward along the shores of Brazil and Guyana. This branch is called the Guyana coast current. The equatorial current has north of the equator an almost uninterrupted progress until it reaches the Windward Islands, but a portion of it impinges against the South American coast and perhaps increases the volume of the northern branch of the south equatorial current. At the Windward Islands all are united, and a portion of the water enters the Caribbean to assist in forming the Gulf Stream. Between the northern and southern portions of the equatorial current is the Guinea current, setting toward the east and southeast into the Gulf of Guinea. It was formerly thought to be a continuation of the North African current, "but later investigation," Findlay says, "seems to point to the fact that it is a flowing back of the waters heaped up to the westward by the prevalent winds." It seems to run strongest in the summer months, when it is felt as far west as longitude 45o, while in the winter it reaches only as far as the twenty-third meridian. In the Northern Atlantic Ocean the Labrador current sweeps down from the Arctic along the eastern shores of Greenland and from Baffin's Bay and passes the coasts of Labrador and Newfoundland, bearing with it vast fields of ice and enormous bergs. Reaching the Gulf Stream, it is said to underrun the latter, and also in part form a counter-current to the southward along our coast as far south as Cape Hatteras, or even to Cape Canaveral.
The Gulf Stream, the grandest and most mighty of any terrestrial phenomenon, receives its waters from the Caribbean Sea through the Straits of Yucatan. It is commonly said that a portion doubles Cape San Antonio and enters the Straits of Florida at once, while another part, after making the tour of the Gulf of Mexico, joins the first in its flow to the northward. Its waters are characterized by a deep blue color, great clearness, and high temperature. The eye can penetrate it to considerable depths, and frequently its meeting with the colder water from the polar regions can be at once distinguished.
It is difficult for the mind to grasp the immensity of this great ocean river. The observations taken at its narrowest point were between three and four thousand in number, surface and subsurface, and a calculation of the average volume passing Cape Florida in one hour gives the enormous sum of 90,000,000,000 tons. If this one hour's water were evaporated, the remaining salt would require more than one hundred times the number of sea-going vessels now afloat in the world to carry it. That this wonderful body is governed by law in all its motions there can be no doubt. It has its daily and monthly variations in velocity, direction, and temperature, changing with as perfect regularity as the tides in a harbor. Nor do I doubt that it has also a yearly fluctuation, and perhaps others occupying a cycle of many centuries to complete.
The Gulf Stream after leaving the Straits of Florida pursues a general northeasterly direction, pressing close to Cape Hatteras, passing between Bermuda and Nova Scotia, and as a defined and permanent stream is soon afterwards lost. Currents are found in the vicinity of the Azores Islands setting about southeast, and also on the coast of Africa setting south, which are sometimes called the southeast extension of the Gulf Stream. Warm water is found off the coasts of Ireland, Scotland, and Norway, giving evidence of a tropical flow, and this is called the northeast extension of the Stream. Whether or not these currents are wholly formed of the water issuing from the Straits of Florida remains to be discussed later.
Man stands with bowed head in the presence of nature's visible grandeurs, such as towering mountains, precipices, or icebergs, forests of immense trees, grand rivers, or waterfalls. He realizes the force of waves that can sweep away light-houses or toss an ocean steamer about like a cork. In a vessel floating on the Gulf Stream one sees nothing of the current and knows nothing but what experience tells him; but to be anchored in its depths far out of the sight of land, and to see the mighty torrent rushing past at a speed of miles per hour, day after day and day after day, one begins to think that all the wonders of the earth combined can not equal this one river in the ocean.
General Historical Account Of The Gulf Stream
Thomas Yocum
Before the time of Columbus's grand discovery of the New World the coasting vessels of the Old must have recognized that there were currents in the Atlantic Ocean which were entirely independent of the tides; but the first indication that currents on the coast of North America were noticed is found in the writings of the Northmen in their description of voyages to America. Several suggestive names were given to prominent objects of discovery, such as Straumsoe (Isle of Currents), Straumsfjorde (Bay of Currents), and Straummes (Cape of Currents), but their exact location can not be identified. Some claim that the voyages extended even to Florida, but it seems probable from later investigations that the points named were all in the vicinity of Cape Cod.
Columbus, before undertaking his voyage of discovery toward the west, resided for some time on the island of Porto Santo, and it was here that he was shown a piece of curiously carved wood that had evidently drifted there from other lands. Strange woods and other floating objects were continually being thrown upon shores of Norway, Scotland, and Ireland, all of which, to a thoughtful mind like that of Columbus, must have induced the belief that there were other lands at no great distance to the west, and so it is probable that to the Gulf Stream in part the world owes the discovery of America.
In actual observations in the Gulf Stream, or rather in the currents contributing to it, Columbus was the pioneer. It is related that September 19, 1492, he sounded with a deep-sea line, and the lead, passing through the surface drift into the dead water below, showed at once that there was a current setting his vessels to the southward and westward. On his subsequent voyages he remarked the strong currents of the Caribbean Sea. He says, for example, " When I left the Dragon's mouth" (the northern entrance to the Gulf of Paria) "I found the sea ran so strangely to the westward that between the hour of Mass, when I weighed anchor, and the hour of Complines, I made 65 leagues of 4 miles each with gentle winds." He also says of the currents entering the Caribbean between the Windward Islands, "I hold it for certain that the waters of the sea move from east to west with the sky, and that in passing this track they hold a more rapid course, and have thus carried away larger tracts of land, and that from hence has resulted the great number of islands."
On his fourth voyage Columbus discovered and noted the strength of the current on the coast of Honduras, although it is probable that at this time the Gulf Stream itself in the Straits of Florida had been found by independent navigators. Peter Martyr says "he left in wryting that sailing from the Island of Guanassa toward the east he found the course of the waters so vehement and furious agaynst the fore part of his ship that he could at no time touch the ground with his sounding plummet, but that the contrary violence of the waters would bear it up from the bottom. He affirmeth also that he could never in one day with a good wynde wynn one mile of the course of the waters.
Columbus speculated as to the cause of these currents. He thought that the equatorial waters followed the motions of the heavens about the world--that is, the rotary motion by which the stars and air revolve about the globe (as was the opinion of the time), so also the water was supposed to partake of the same motion.
John and Sebastian Cabot, in 1497, crossed the North Atlantic Ocean, rediscovering the coast of Labrador. From this point they steered to the southward and westward, "so coasting still by the shore that he was brought so far into the south by reason of the land bending so much to the southward that he was then almost equal in latitude to the sea called Fretum Herculeum, having the north pole elevate in manner in the same degree. He sayled likewise in this track so far toward the weste that he hadde the Island of Cuba in his left hande in manner in the same degree of longitude." * * * "He sayeth that he found the like course of the waters towarde the west, but the same to run more softly and gently then the swift waters which the Spanyards found in their navigation southward."
It is probable that the Cabots did not double Cape Hatteras and discover the Gulf Stream. It is thought by some that they entered the Straits of Florida, but from the testimony of Peter Martyr, quoted above, they were north of Hatteras and probably in the vicinity of the Delaware, but in the longitude of Columbus's discoveries in the West Indies. They did, however, notice the fact that a gentle counter current existed.
The Cortereals, between 1500 and 1502, on several voyages extending from Labrador toward Cuba, probably crossed the Gulf Stream and may have recognized its strength, but very little is known as to the exact localities visited.
In the year 1508 the Island of Cuba was for the first time circumnavigated. Sebastian de Ocampo, under the authority of the Governor of Hispaniola, sailed along the northern coast of the island through the old Bahama Channel and around the western point, Cape San Antonio. In this voyage eight months were occupied, and as it was against the Gulf Stream it would seem that he must have noticed it. As the times demanded however the custom of secrecy on all expeditions, no record has been left of the fact.
The first record, on which the evidence is satisfactory, of the discovery of the Gulf Stream current, is that of Ponce de Leon in his expedition in 1513 in search of the fountain of youth. In company with the afterwards famous navigator, Antonio de Alaminos, he sailed from Porto Rico, along the northeastern side of the Bahamas, and crossed the Gulf Stream somewhere above Cape Canaveral. After reaching a latitude of about 30o north he turned and skirted the coast as far as Tortugas, thus stemming the current for a distance of several hundred miles. Referring to these currents, their journal says that they saw a current which, though they had a good wind, they could not stem. It seemed that they were going through the water fast, but they soon recognized the fact that they were being driven back and that the current was stronger than the wind. Two vessels, which were somewhat nearer the coast, came to anchor; the third vessel, a brig, being in deeper water, could not anchor, and was soon "carried away by the current and lost from sight although it was a clear day." Ponce de Leon, on this expedition, crossed the stream no less than four times, and Alaminos received his first apprenticeship in its navigation, which in after years proved to be of great benefit to him.
During the next few years the Spaniards crossed and recrossed the Stream between Cuba and Florida many times in their search for gold, and of course gained much practical knowledge of the strength and velocity of its currents.
It is interesting to note the speculations of the day as to the cause of this startling phenomenon, and its result on the sailing route to Europe. The which, while I consider I am drawn into no small ambyguetie and doubt, whyther those waters have their course which flowe with so continual a tract in the circuite from the easte, as though they fledde to the weste never to retourne, and yet neyther the weste thereby any whit more fylled nor the east emptied.
If we say that they fall to their centre (as in the nature of heavier things) and assign the equinoctial hyll to be the centre (as some affirme), what centre shall we appoint to be able to receive so great abundance of water, or what circumference shall be found wet.
Many think that there should be certayne large strayghts or entrances in the corner of that great land which we describe to be eight times larger than Italie, and the corner of that land to be full of gulfes, whereby they suppose that some strayghts should pass through the same lying to the weste side of the Island of Cuba, and that the said strayghts swallowe up those waters and so conveys the same into the weste, and from thence again into the easte ocean or north seas as some think. Others will, that the Gulf of that great lande, be closed up and the lande to reach far to the north in the back side of Cuba, so that it embrace the north landes which the frozen sea encompasseth under the north pole, and all the lande of these coasts should joyne together as one firme lande. Whereby they conjecture that these waters should be turned about by the object or resistance of that lande so tending toward the North, as we see the waters turned about the crooked banks of certayne ryvers. But this agreeth not in all points, for they also who have searched the frozen sea, and sayled from thence into the weste doe likewise affirme that those north seas flowe continually toward the weste although nothing so swiftly. * * * Wherefore it is not only more likely to be true but also of necessity to be concluded, that between both these landes hitherto unknown, there should be great certayne open places whereby the waters should thus continually passe from easte into the weste, which waters I suppose to be driven about the Globe by the incessant moving and impulsion of the heavens, and not to be swallowed up and cast out again by the breathing of Demo-gorgon as some have imagined, because they see the seas increase and decrease, flowe and reflowe. The same writer continues at a later date:
Let us now therefore speake somewhat again of the later news and opinion as concerning the swift course of the sea toward the weste about the Coast of Paria. So it is therefore that Andreas Moralis, the pilot, and Ouidas (of whom we have made mention before) repayred to me at my house in the time of Matrite. As we met thus together there arose a contention between them two as concerning this course of the ocean. They both agree that these landes and regions pertayning to the Dominion of Castile, do with one continuale tract and perpetual bond embrace as one whole firme lande or continent all the mayne lande lying to the north of Cuba and the other islands, being also northwest from both Cuba and Hispaniola. Yet as touching the course of the waters they vary in opinion; for Andreas will, that his violent course of the water be received into the lappe of the supposed continent, which bendeth so much and extendeth so farre toward the north, as we have said, and that by the object or resistance of the lande so bending and crooking the water as it were, rebounde in compasse and by the force thereof be driven about the north side of Cuba and the other islands excluded outside the circle called Tropicus Cancri, where the largeness of the sea may receive the waters falling from the narrow streams and thereby represse that inordinate course by reason that the sea is there very large and great.
The Admiral himself, Diegas Colonus, sonne and heyre of Christophorus Colonus the first finder of these landes, being demanded of me what he found or perceived in sayling to and from, answered that there was much difficultie in retourning the same way by which they go; but whereas they first take their way by the mayne sea toward the north before they direct their course to Spayne, he sayth that in that tract he felt the shippe sometymes a little driven back by the contrary course of the waters yet supposed that this chaunceth only by the ordinary flowing and reflowing of the sea, and the same not to be enforced by the circumflection of the water rebounding in compass as we have sayde; but thinketh that this mayne lande or supposed continent should somewhere be open.
Ouidas agreeth with Andreas Moralis as touching the continual adherence of closeness of the sayde continent, yet neither that the water shoulde so beat agaynst the bending back of the weste lande, or be in such sort repulsed and driven into the mayne sea; but sayth that he hath diligently considered that the waters runne from the deepest and wyddest of the mayne sea toward the weste. Also that sayling near into the shore in small vessels, he found the same waters retourne agayne toward the east, so that in the same place they runne together with contrarie course.
Thus have we made you partner of such things as they have given us and written their divers opinions. We will then give more certayne reasons when more certayne truth shall be known. We must in the meantime leane to opinions until the day come appointed of God to reveal this secret of nature with the perfect knowledge of the pointe of the pole Starre. It is certainly most remarkable, when we consider how imperfect was their knowledge of the form or extent of the continent, that their views should have been so near the truth. The Gulf of Mexico was not discovered until 1517, and explored the year after, when the current on the western of the Straits of Yucatan must have been found. Ocampo, in circumnavigating Cuba, judging from experience of the present day, could have found only the tidal currents in the vicinity of Cap San Antonio. The current in the passages in the eastern Caribbean was known to be strong and westerly, and on the Honduras coast the same. Alaminos and Ponce de Leon had found the current in the Straits of Florida, and evidently some of the speculators determined that the land was continuous and in some way the two parts of the flowing stream of water were connected.
Antonio de Alaminos was without doubt the most experienced navigator and pilot in the West Indian waters. He had been chief pilot with Columbus on his last voyage, had been with Ponce de Leon around and among the Bahamas and along the coast of Florida from St. Augustine to Tortugas, and had crossed and recrossed the stream several times. He had afterwards been with Cordova and Grijalva exploring the coast of Yucatan and the Gulf of Mexico. He was familiar with the fact that there was a passage north of Cuba from Gulf to the Ocean, but beyond the Straits to the northward was unknown to him. He thought, however, as Herrera says, "that these mighty currents ought to empty somewhere into an open space." Upon fitting out the expedition for the conquest of Mexico, Cortez gave the chief command of the fleet to Alaminos, and when, later, it was thought necessary to send dispatches and presents to Spain, he was given the fastest vessel to carry the Envoys. Instructions were given him to hold his course north of Cuba and pass into the Atlantic through the Straits of Florida, not touching at any port in the West Indies. Probably this route was suggested to Cortez by Alaminos as being most favorable for a quick passage, and one by which he would be sure to avoid a chance meeting with an enemy either of his own or of a foreign country. The vessel sailed from Vera Cruz July 26, 1519, and after disobeying his instructions by making a stop at the port of Marien on the north side of Cuba, Alaminos passed through the Straits of Florida and reached Spain in safety. It is of course doubtful how far he followed the Gulf Stream, but it is probable that he did so well up the coast toward Cape Hatteras. His voyage changed the course of navigation from the West Indian ports and contributed largely toward the growth of Havana. This port soon became the rendezvous of the West Indian trading fleet, the distributing point of goods from Europe, and the starting port for the return home.
During the half century following the remarkable voyage of Alaminos, there were expeditions without number to the West Indies and the mainland, and while there are minute and detailed descriptions of the land, products, and people, yet scarcely anything is said of the sea currents.
Sir Humphrey Gilbert, writing before 1576, says that all the waters of the ocean "run by nature circularly from east to west, following the diurnal motions of the Primum Mobile." He traces the motions of the waters from the south of Africa and says that from there it strikes over to America. Not finding free passage "it runs all along the eastern coast of that continent northward as far as Cape Freddo, being the farthest known place of the same continent toward the North, which is about 4,800 leagues." He thinks that even if this current has not been traced all along the coast of America, "still it must exist either in uppermost or the nethermost part of the sea." For the reason that this current must have a free passage somewhere Gilbert says "it must either flow around the north of America into the South Sea or it must needs strike over upon the coasts of Iceland, Norway, and Finmark." He adopts the first of the alternatives, as he is anxious to prove the existence of the Northwest Passage. In the journal of his last voyage he mentions that in 50o north latitude they saw ice being carried to the southward, and so conjectured that a current must be setting in that direction. In 1579 and again in 1583 he made two unsuccessful attempts to establish colonies on the east coast of the present United States, and it is curious to see how great was the influence of the Gulf Stream, even at that time, in directing navigation. In considering the advisability of taking the southern passage from England or the more direct but more difficult northern one, he says, "by what way to shape our course, either from the south northward, or from the north southward. The first course, that is, beginning south, without all contraversie was the likeliest wherein we are assured to have commoditie of the currents, which from the Cape of Florida setteth northward, and would have furthered greatly our navigation, discovering, from the foresaid cape toward Cape Breton and all these lands lying to the North." The advantage of being able to provision the vessel at the Banks of Newfoundland led them to decide upon the northern route "although contrareity of currents descending from the Cape of Florida into Cape Breton and Cape Race would fall out to be great and irresistible impediments unto our further proceeding for that year, and compel us to winter in those northern regions."
The records of the voyages of Martin Frobisher are of great interest as showing the gradual extension of knowledge on the subject of ocean currents. He crossed the northern Atlantic six times during the years 1576-'77-'78. In the account of this third voyage he says: Sayling toward the northwest parts of Ireland we mette with a great current from out the southwest, which carried us [by our reckoning] one point toward the northeastward of our said course, which current seemed to us to continue itself toward Norway and other of the northeast parts of the world, whereby we may be induced to believe that this is the same which the Portugese mette at Capo de Buong Speranza, where, stricking over from thence to the Straits of Megellan and finding no passage there for the narrowness of the sayde Straits, runneth alongue to the great Bay of Mexico, where also having a let of land it is forced to strike back again toward the northeast, as we not only here but in another place also further northward by goode experience this year have found. How the currents returned to the Cape of Good Hope from the "northeast parts of the world" is not stated, but the general course of the Atlantic system is very fairly laid out.
About this time there appeared the theory in "La Cosmographie" that the currents in the Straits of Florida were caused by the rivers emptying into the Gulf of Mexico, and this theory has been held by writers at much later dates. In 1596 it is recorded by D. Layfield, chaplain of the Earl of Northumberland, that between Bermuda and the Azores they thought they observed a current,but shortly before arriving at the latter they were sure of a current setting southward.. The next expedition to that of Gilbert, for settling Virginia and North Carolina, was under Captains Amadas and Barlow. They took the southern passage, as did also all of those under Raleigh. Some of these left the Caribbean east of Cuba, and others continued to the westward and passed through the Straits of Yucatan and Florida.
In 1590 John White, who had been Governor of the colony at Roanoke, referring to the portion of the voyage from Florida Keys to Virginia, says: "We lost sight of the coast and stood to sea for to gaine the helpe of the current, which runneth much swifter farre off than in sight of the coast, for from the Cape of FLORIDA to Virginia, all along the shore, are none but eddie currents setting to the south and southwest." This is the first instance in which there is indicated a knowledge of an approximate position of the axis of the Stream.
In 1606 an observation is recorded by Lescabot, which is evidently a meeting of the Labrador and Gulf Stream currents. He noticed that while in latitude 45o and "six times 20 leagues to the eastward of the Banks of Newfoundland, we found for the space of three days the water very warm, whilst the air was cold as before, but on the 21st of June quite suddenly we were surrounded by fogs and cold that we thought to be in the month of January, and the sea was extremely cold." He attributes this to the ice from the north which comes floating "down from the coast and sea adjoining to Newfoundland and Labrador, which is brought thither by the sea in her natural motion."
The influence of the Gulf Stream in the colonization of North America was about this time very great. In 1606 the English divided their possessions into two parts, the northern part of Virginia (new England and vicinity) was one, and the present North Carolina and Chesapeake Bay region the other, and for each a company was established and commissioned by the King. The route used in going to the first was that tried in 1602 by Capt. Bartholomew Gosnold, crossing the Atlantic on about the fortieth parallel, while the southern expeditions held the old passage through the trades and Caribbean. The Dutch vessels bound to New York adopted the West Indian route, so that Nantucket really became the dividing line of travel, and a difference in destination of a degree in latitude necessitated a difference of thirty degrees in route. This seems only to be accounted for by the real or imaginary assistance of the winds and currents in one and the impediment of the Stream in the other. After the English and Dutch settlements became firmly established and crossing the Atlantic a common thing, the personal experience of navigators was no longer thought to be of sufficient importance to print, and the time had not yet arrived for adopting a plan of collecting ship's journals and publishing such nautical information from them as would be of value to others. The writers on the subject, however, must have had access to these journals and corrected and improved their ideas on the subject of currents, and in the latter half of this century many works on hydrography appeared.
In 1650 Varenius gave the most complete description of currents which had been issued up to this time. He classified them into perpetual and periodical, special and general. The system of which the Gulf Stream forms a part he placed as a perpetual special motion of the sea, and describes it as a gigantic Stream beginning at the eastern Capes of Brazil, flowing from south to north and ending toward Florida. He adds, "a similar current from south to north is observed along the Philippine Islands and toward Japan." He also wrote that "some Copernicans, as for instance Keppler, pretend that also the movement of our globe contributes not a little toward it" (the currents), "because the water, not being adherent to the earth but only in a loose contact with it, cannot follow the quickness of its motion toward the east, but is left behind toward the west, so that the sea does not move from one part to the other, but on the contrary it is the earth which quits or leaves the parts of the sea, one after the other."
In 1663 Isaac Vossius wrote a work entirely devoted to the motion of wind and sea, and in it particularly describes most of the currents known in the present day. He says:
With the general equatorial current, the waters run toward Brazil, along Guyana, and enter the Gulf of Mexico. From there, turning obliquely, they pass rapidly through the Straits of Bahama. On the one side they bathe the coasts of Florida and Virginia and the entire shore of North America, and on the other side they run directly east until they reach the opposite shores of Europe and Africa; from thence they run again to the south and join the first movement to the west, perpetually turning in this manner circuitously. He emphasizes this by saying that "a ship without sails and sailors might be conveyed solely by the force of the currents from the Canary Islands to Brazil and Mexico, coming back from there by way of the Florida stream toward Europe on a route some 4,000 German miles in length." Vossius's theory as to the cause of the ocean circulation was that the heat of the tropical sun attracted the ocean and at the same time increased its bulk and formed, as it were, a long mountain of water, "to which the vessels even have some difficulty in ascending when they sail toward the line." He concluded that the sun carried this mountain of water toward the South American shore, where it broke and ran along the coasts. A French hydrographer, George Fournier, some years later propounded a theory almost the opposite. It was that the sun evaporated enough water in the tropics to make a deep valley, and therefore the water from the poles was forced to run toward the equator along the coast of Africa to replace the lost water. He though that the depression always ran before or with the sun and the arriving polar water behind the sun and the rotary system of currents was thus produced.
In 1678 Athanasius Kircher, a Jesuit, gave to the world in his "Mundus Subterraneus," the first published chart showing the system of ocean circulation and the Gulf Stream. He says of the causes of the Gulf Stream:
This motion touches many things, whether partly from the general motion of the trade winds against the opposing shores of that region and thence again reflected, which they call the Sailor's Current, or from wind-storms, or finally from the flow and the reflow caused by the moon's force. He was, however, a strong believer in submarine abysses as the cause of vortices and special currents. In 1685 a German named Happelius published another chart of Ocean currents
quite similar to Kircher's. In his work he says:
The general motion of the Ocean goes from east to west, and it is most obvious in the torrid zone. The sun is the cause of this general course of the sea as well as of the trade winds. The particular motions of the sea are of two kinds, one on a straight line and the other with a circulating or whirling movement. Of those which run in a straight line some are constant, regular, and perpetual the whole year through. Some show themselves only at times and change even in direction, are irregular, depending much on the direction of the wind. In the Atlantic from the Brazilian Cape to St. Augustine toward the Antilles and Florida is a constant and perpetual course of the sea from the south to north. About this time the question began to be agitated in the minds of scientists as to how the strange fruits and woods were deposited on the shores of Ireland, Scotland, and other northern lands. The molucca bean was frequently found there, and the fact was thought to be proof of either a northeast of northwest passage to the East Indies. In 1696 Dr. Hans Sloan proved that these beans came from Jamaica. He says:
It is very easy to conceive that, growing in Jamaica, and having got to sea by the rivers, they may be carried by the winds and by the current which is forced through the Gulf of Florida, going there constantly east into the North American Sea; but how they should come the rest of their voyage I can not tell, unless it be thought reasonable that the beans, being brought north by the current from the Gulf of Florida, are put into the westerly winds' way, and may be supposed by this means at last to arrive at Scotland. This is exactly the opinion of many people at the present day.
In 1702 and again in 1720 the fact was stated that the Gulf Stream ran the strongest in the Straits of Florida during strong northerly winds, and as an explanation of this phenomenon Professor Leval thought that it could only be accounted for by the supposition that during the north winds in the channel in the Gulf of Mexico they were blowing from a more northwesterly direction, and in this was pushed the waters of the Gulf into the Straits and so forced them through the latter with increased velocity. The French route from Louisiana to Europe followed the Gulf Stream along the North Atlantic coast toward the Banks of Newfoundland, differing considerably from the more southern route taken by the Spaniards, but while adopting this most expeditious track they went to the other extreme in sailing from their Gulf to their West Indian possessions. They followed the Stream well up toward the Grand Banks, then south to the trade winds and west to their port.
Up to this time, with the exception of Kircher and Happelius in 1679 and 1685, there seems to have been no attempt to indicate the Gulf Stream upon the charts, and even these were more for scientific interest than for the practical benefit of mariners. One chart published in 1630 by the Earl of Northumberland gave the words "Corrento verso Greco," placed about half a degree from Cape Hatteras; but with this exception up to the first half of the eighteenth century, charts generally only show an inscription between Cuba and Florida, "Canalis Bahama versus Septentrionem semper fluit," or its translation into other languages. About the middle of the eighteenth century arrows appeared on the charts of the British colonies to indicate coast currents, and at the same time French charts indicated currents in the Caribbean and in the Straits of Florida in like manner. In 1772 detached indications of the Gulf Stream currents appear, and in 1775 on a special map of Carolina there are arrows near the coast pointing to the southward and westward, and farther off the coast pointing North.
That the want of knowledge as to the limits of the Stream was felt is shown by the length of time consumed in passages between the same ports in opposition directions. A voyage from Boston, Massachusetts, to Charleston, South Carolina, would sometimes take three or four weeks, while a return trip would frequently be made in one week. The coasting captains and whalemen, however, were gaining experience regarding the Stream, and to the latter more than all others, up to the time of the Revolutionary War, Franklin was indebted for the information which led to the publication of his chart of the great Ocean current.
These whalers extended their search as far south as Bahama and as far east as Newfoundland, or even to the longitude of the Azores. They discovered that the whales appeared to the north of a certain line and to the south of another line, and were but rarely seen between the two, and these lines they concluded were the limits of the Gulf Stream. The whale fishery soon became the school for American navigators, particularly of New England vessels, and in this way knowledge of the Gulf Stream was introduced into the commercial traffic of the times. The American shipmasters, from their superior information on the subject of currents, inaugurated a change in the sailing route from Europe, by which they could save two weeks or more in the passage. From England they crossed the Newfoundland Banks in about latitude 44 and 45 degrees, and thence on a course inside the limits of the Stream.
Gulf Stream Investigations From The Time Of Franklin To Those Made By The U.S. Coast Survey
How long the American fishermen had been acquainted with the secret of the Gulf Stream's peculiarities before it was brought to the notice of Franklin it is impossible to state. They kept the secret, however, until, as Franklin says--
About the year 1769 or 1770, there was an application by the Board of Customs at Boston to the Lords of the Treasury at London, complaining that the packets between Falmouth and New York were generally a fortnight longer in their passage than the merchant ships between London and Rhode Island, and proposing instead of New York that for the future they should be ordered to Newport.
Being then concerned in the management of the American Post-Office, I happened to be consulted on the occasion, and it appearing strange to me that there should be such a difference, especially when the merchant ships were generally deeper laden and more weakly manned than the packets, and had from London the whole length of the river and channel to run before they left the land of England, while the packets had only to go from Falmouth, I could not but think the fact misunderstood or misrepresented.
There happened then to be in London a Nantucket sea captain of my acquaintance, to whom I communicated the affair. He told me he believed the fact to be true, but the difference was owing to this, that the Rhode Island captains were acquainted with the Gulf Stream, while those of the English packets were not. "We are well acquainted with that stream, because in our pursuit of whales, which keep near the sides of it but are not met within it, we run along the side and frequently cross it to change our side; and in crossing it have sometimes met and spoke with those packets who were in the middle of it and stemming it. We have informed them that they were stemming a current that was against them to the value of 3 miles an hour and advised them to cross it, but they were too wise to be councelled by simple American fishermen. When the winds are light," he added, "they are carried back by the current more than they are forwarded by the wind, and if the wind be good the subtraction of 70 miles a day from their course is of some importance."
I then observed that it was a pity that no notice was taken upon the charts, and requested him to make it out for me, which he readily complied with, adding directions for avoiding it in sailing from Europe to North America. I procured it to be engraved by order from the General Post-Office on the old chart of the Atlantic, at Mount & Page's, Tower Hill, and copies were sent to Falmouth for the captains, who slighted it, however, but it has since been printed in France, of which edition I hereto annex a copy.
Franklin's theory on the subject of the cause of the Gulf Stream is given in the same report.
This stream is probably generated by the great accumulation of water on the eastern coast of America between the tropics by the trade winds which constantly blow there. It is known that a large piece of water, 10 miles broad and generally only 3 feet deep, has, by a strong wind, had its water driven to one side and sustained so as to become 6 feet deep, while the windward side was laid dry. This may give some idea of the quantity heaped upon the American coast, and the reason of its running down in a strong current through the islands into the Bay of Mexico and from thence proceeding along the coasts and banks of Newfoundland where it turns off towards and runs down through the Western Islands. Franklin did not press his new chart on the notice of the English ship captains after they had once rejected it, but for the time being suppressed it, for political reasons, until the conclusion of the War of Independence. In the mean time, in 1775-'76, and in later years, whenever he made a voyage across the Atlantic, he took observations of the surface temperature of the Ocean.
I find that it is always warmer than the sea on each side of it, and that it does not sparkle in the night. I annex hereto the observations made in two voyages and may possibly add a third. It will appear from them that the thermometer may be a useful instrument to the navigator, since currents coming from the northern into southern seas, will probably be found colder than the water of those seas as the currents from southern seas into northern are apt to be warmer. On his last voyage, in 1785, he made the first attempt in submarine temperatures at moderate depths, using a bottle up to 20 fathoms, and afterwards a cask with valves in each end. Off the Delaware, in 18 fathoms, he discovered that the water at this depth was 58o, which was 12o colder than at the surface.
Although Franklin's chart of the Gulf Stream, published in London, had been rejected by the English shipmasters in 1770, it was certainly adopted by writers on hydrography. The information was given to the public through these works, and the name Gulf Stream came into general use. The importance, too, of gaining all possible information about this mighty river seems to have been realized at this time, and consequently nearly all government vessels were instructed to observe its phenomenon whenever opportunity offered. Among the most prominent investigators was Dr. Charles Blagden, of the Royal Army, while with the British fleet going to and in the American waters in 1776-'77. He observed the temperature in crossing the stream off Cape Fear, and also off the Chesapeake, communicating his results to the Royal Society, in 1781, in a letter urging the essential advantage to be derived by the use of the thermometer. These two, Franklin and Blagden, were the first to demonstrate the usefulness of that instrument, and, since the time of Alaminos, no discovery of like importance had been made which bore so directly on the question of utilizing this great river to the purposes of man's welfare.
Soon after Franklin's and Blagden's discoveries, Mr. Pownall, formerly Governor of Massachusetts, published in 1787 a large chart and a volume of Hydraulic and Nautical Observations on the Currents of the Atlantic Ocean. On this chart the Gulf Stream is laid down closely approximating to that of Franklin's
. He also gives the correct course or tracks which vessels should take; that to Boston "along and beyond the northern edge of the Gulf Stream." To Virginia and Carolina he urged one in about latitude 35o instead of running down to 20o, as was usual.
Franklin on his last voyage was accompanied by a nephew, Col. Jonathan Williams, who was of great assistance in the thermometrical observations and record of results. Such interest was awakened in the mind of Williams that he was led to continue the experiments begun by his uncle. In a memoir read before the American Philosophical Society in 1790 he confirmed Dr. Franklin's account of the temperature of the Stream, and also advanced the theory that banks, shoals, and coasts might be discovered by the use of the thermometer. Williams published a work in 1799 on thermometrical Navigation, containing a chart of the Gulf Stream
and the temperature of the water on adjacent banks. In 1800 a paper was read by Capt. William Strickland on the use of the thermometer in navigation. In his voyages across the Atlantic he had kept daily and sometimes hourly observations of surface temperature, in order to test the theory of Colonel Williams. His investigation was valuable from the discovery of the warm northeasterly extension of the Gulf Stream, for he found in latitude 46o 47' North and longitude 38o 35' west, a temperature of 68o. He says, of this northeast extension, "it probably continues in about a northeast direction entirely across the Atlantic till it ultimately strikes the coasts of Ireland and the Hebrides, after having lost, in its long course in these northern latitudes, much of its heat, and at last being reduced to the temperature of the sea through which it flows." He recommended the employment of vessels to define the limits of this northern branch between latitudes 47o and 60o by the use of the thermometer. Although others before Strickland had noticed floating weeds and American woods in these northern localities, and even Cabot had remarked upon the fact of the beer in the hold of his vessel getting warm, thus surmising a warm current, yet no one seems up to this time to have declared its existence a fact, based upon actual experience and scientific observation.
At the beginning of the nineteenth century, the subject of ocean currents was a favorite one for investigation by the navigator and hydrographer. The thermometer was the accepted instrument in the research, and by the chronometer, which was becoming of greater value and more generally used, the difference between the dead reckoning and the observed positions could be determined with greater accuracy. As we shall see later, from the time of Franklin and Blagden, for more than a century, all the investigation of ocean currents was based solely upon these two instruments, the thermometer and the chronometer, and upon, what in effect is the same as the latter, the drift of bottles, In the year 1802 the first bottle experiments seem to have been inaugurated, the English ship Rainbow throwing overboard several in the NORTH Atlantic, and at intervals these experiments have been continued in all parts of the world up to the present day.
A remarkable thermometrical voyage was made in 1810 by the packet Eliza, from Halifax to England. It was found that in the midst of the warm water of the stream there existed patches of cool water of 10o to 15o lower temperature than the surrounding sea, and having a diameter of over 200 miles. They were thought to have been caused by icebergs and floes which had entered and been melted in the Gulf Stream. In 1811 and 1812, Sir Philip Broke made a great number of observations in the Gulf Stream and described its characteristics. Among other things he states "that beyond the southern boundary of the stream, from the Azores toward Bermuda and the Bahamas, there is a strong set to the southwest or west southwest, that when this countercurrent arrives opposite the outfall of the Florida or Gulf Stream it turns to the southeast along the outer side of the Bahama Archipelago, receiving into its body a large offset of the Gulf Stream which rounds the Matanilla Bank." Another alleged characteristic of the current began to appear in the nautical works of the early part of the century: "That easterly winds press the current toward the American coast, and that the consequences of this pressure are that the breadth of the Stream and its distance from the shore is diminished and it velocity increased, and that in the contrary, winds which blow from the coast produce contrary effects."
Capt. John Hamilton gave to the American Philosophical Society, in 1825, the observations made by him during twenty-six voyages to and from Europe. They consist of temperature of air and water, current of the Gulf Stream for different months, average temperature of the water on soundings off the Delaware, Georges Bank, and on the coast of Ireland. Some of the conclusions arrived at by Captain Hamilton were of great value at the time. He decided that it was impossible to define the limits of the current of the Gulf Stream, owing to the variable influence of the wind; that after it passes the Grand Bank the main Stream proceeds to the southward, while several ramifications, generally not very strong, branch off to the northeast and from that to the east, with countercurrents in the intermediate spaces; that by the frequent use of the thermometer the navigator may always discern where he touches the Gulf Stream, and take advantage of its current or avoid its influence. He further remarks:
I was for a long time almost induced to conclude that some of these currents, particularly those which prevail between the coast of Newfoundland and Europe, were periodically running half the time in one direction and half the time in the other, and the foregoing tables seem to strengthen this conclusion, except the countercurrents near the edge of the stream.
When the current from the northward prevailed to any great extent, a set in the opposite direction near the bank of Newfoundland and on the west coast of Ireland were always observed. The celebrated German, A. von Humboldt, published in 1814 a valuable description of the Gulf Stream, the result of his own observations in crossing it no less than sixteen times, as well as of all the information he could collect from the journals of navigators who had been possessed of the necessary means for exact astronomical observations at sea. He decided that the Gulf Stream was not the same in all seasons of the year, but that its that the Gulf Stream was not the same in all seasons of the year, but that its force and direction depended to a large extent upon changes in the trade winds, and also, that the general torpidity of the ice in the Arctic in the winter and its melting in the summer, influenced it. Regarding the directions of ocean currents he says:
Considering the velocity of the fluid elements which, in different latitudes, in consequences of the earth's rotation, is different, one should be tempted to think that every current from south to north ought to have at the same time a tendency to the east, and, vice versa, a current from north to south a tendency to the west. He published a chart of the Gulf Stream in which he depicted its changeable limits as he believed they were.
During the next few years many navigators cruised in and examined the Gulf Stream, more particularly however in the vicinity of the route between Halifax and Bermuda. One of them in May 1821, in about 64o west longitude remarked the fact that he observed a vein of cool water of a temperature of 54o between 72o and 73o, which seems to be the first time this phenomenon was noticed. The celebrated Englishman, Capt. W. Scoresby, investigated the northern extension of the stream, and discovered in the vicinity of Spitzbergen that an under stratum of water was generally warmer than that at the surface. He believed that the warmer water, though of similar specific gravity was in this case, the most dense, and that sea water followed the same law as fresh water with regard to extreme of density, being a few degrees above its freezing temperature. To this he attributed the fact that the polar ice in these waters could not extend far to the southward, and Humboldt adopted the same. The latter says: "In those regions which are warmed by a current from the southwest, navigation is uninterrupted even in the midst of the strongest winter."
Col. E. Sabine, in 1822 was a member of an expedition organized for the purpose of making experiments to determine the figure of the earth. Sailing from England he went to Madeira and to Sierra Leone, through the Caribbean and the Straits of Florida to New York and thence to England, thus making the complete circuit of the warm Atlantic currents. In his observations on ocean temperatures he found in the eastern Atlantic a body of water very much warmer than normal, and attributed this fact to an unusual elevation of the Gulf of Mexico and the Caribbean, due to abnormally strong trade winds. The weather was so unusual in the southern parts of Great Britain and in France as to have excited general remark, as "most extraordinary hot, damp, stormy, and oppressive," and that in November and December gales from the west and southwest were almost without intermission. We here see, not so much the direct influence of the warm water of the stream on the climate of England and France as the effect of the westerly and southwesterly gales.
During the first quarter of this century the British admiralty office had collected a great quantity of material on the subject of ocean currents and meteorology, most of which had never become known to the public. Mr. James Rennell, who had devoted his life to the subject of geography, and particularly to ocean currents, was given the task of compiling and collecting the data. He combined the results on large charts of the ocean which were the administration of the day, and also wrote a volume on "An investigation of the subject of the currents of the Atlantic Ocean." He died, however, before its entire completion, but two years later (1832) it was published by his daughter Lady Radel. In the charts were embodied the general courses of the currents with the limits of variations, the directions of the winds, accompanied by the date of observation, the depth and temperature of the sea, and some of the tracks of the vessels making specially important scientific observations.
Major Rennell adopted Dr. Franklin's theory as to the principal cause of ocean currents and divided them into two classes: Drift currents, caused by the effect of constant or long-continued winds on the surface of the water, and stream currents, which are formed by the accumulation of water by the drift current meeting an obstacle and thrown sideways or out of its usual course. The Gulf Stream he placed in the latter class, but concluded that it turned south toward the Azores and was lost, while he considered the movement of water in the northern part of the North Atlantic a drift current impelled by the prevailing westerly winds, and these also were the cause of the African current.
From this investigation he pronounced it to be abundantly proved--
(1) That there existed a change in the position and breadth of the column of warm water from time to time.
(2) That the breadth varied at time in the proportion of more than two to one.
(3) That these changes had been observed sometimes to be very sudden--as, for instance, it had once been found to be 140 miles in width, and ten weeks later at the same spot to be 320 miles broad.
(4) That these changes did not follow any regular course of season, for it was 320 miles wide in May, 1820, and only 186 miles in May 1821, nearly at the same place.
(5) That on the northern side of the stream the body of warm water is more permanent than to the south, and also that the warmest water is found to the North, as if indicating the strongest part of the stream there.
(6) That the existence of warm water does not necessarily indicate the presence of the stream, but must be regarded as an overflowing or deposit of superabundant water, or even from a counter current.
(7) That there were without doubt veins of colder water within the body of warm water.
He pointed out the fact, and, indeed, it exists at the present day, that the position of the Stream east of Cape Hatteras is but imperfectly known, and that notwithstanding the great number of observations at his disposal, a want of system in their collection, the isolated and unconnected facts obtained by different observers at different season, and errors in determining longitude made it impossible at that time to state where the borders of the Stream should be placed. The observations discussed by Major Rennell were of the surface temperature, and we shall see later how great is the influence of the wind in spreading the warm water of the Stream without carrying the current with it. His work was the most valuable collection of results that had been made, and while some of his conclusions have since been disproved, it is a remarkable fact that he should have arrived at so near the truth in many of them. An index of his currents is shown here.
For several years after the death of Major Rennell, observation
