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the gulf stream by john elliot pillsbury

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CHAPTER III.


GULF STREAM INVESTIGATIONS MADE BY THE U.S. COAST SURVEY
UNTIL 1884 AND THOSE CONTEMPORARY WITH THEM

We have now reached the point in the history of the Gulf Stream investigation where, for the first time, can be described a systematic and extensive examination into its secrets. Research had been going on for years in a casual way, data collected when chance offered, and at any point, but under the direction of no one who had the authority to say to the observers when, where, and how they should search. The scope of the Coast Survey only contemplated an examination of the Gulf Stream in the portions adjacent to the coast of the United States, but the laws have since been changed so as to include the Sargasso Sea and the Japan Stream, a study of these being considered advantageous to the commercial and scientific interests of this country and the world at large.

In 1842 a report was made by Admiral Sir Francis Beaufort urging the British Admiralty to undertake the work. The importance of an examination of the great rivers emptying into the Atlantic, to whose influence the Gulf Stream had been attributed, was suggested, and the details of a plan were given for a survey of the Stream from the Gulf of Mexico to the shores of Europe.

This plan proposed the employment of three steamers and one sailing vessel. One steamer was to remain in the Gulf of Florida for the purpose of keeping a continuous record of temperature and velocity at the point, The sailing vessel was to drift along in the axis of the Stream, while the other two steamers were to operate from the axis to the edges in conjunction with the sailing vessel.

When Prof. A.D. Bache assumed the direction of the Coast Survey, he formulated a complete method of administration and included in it the systematic exploration of the Gulf Stream. The plan first adopted, based upon the knowledge of the general features of the Stream, was as follows, but it naturally was modified by deductions and inferences from new facts which were brought to light as the Survey progressed:

I. To refer the observations to a medial line or axis, on each side of which it would be more or less in its temperatures, and to run sections perpendicular to this line across the whole width of the Stream.

II. To start from points on the coast whose positions are well known, and to determine by the best means known to nautical astronomy the position of the vessel at frequent intervals, and to check these results if necessary by a return to the coast.

III. To occupy positions at which the temperatures at different depths would be determined, the frequency of which would depend upon the greater or less rapidity of the change of temperature.

As regards seasons for explorations, the summer was regarded as the most favorable for the greater part of the Stream, for the reason that the winter season, at which time the storms and cold rendered observation more difficult, is also the season in which the equilibrium of the currents would be most disturbed by the rapid cooling of the water. Sounding in winter in stormy weather (with rope) was hardly practicable, and the results obtained were liable to great inaccuracies.  

In the spring of 1845 the brig Washington was commissioned and placed under the command of Lieutenant C.H. Davis, U.S.N., and the following instructions were given him. The first part is quoted almost in full, to show the clearness with which Professor Bache saw the details necessary for such an investigation in order to establish the laws of the Stream in the best manner with the instruments available at that time.  

Professor Bache says:  

The following questions should be examined:

First. What are the limits of the Gulf Stream on this part of the coast of the United States, at the surface and below the surface?

Second. Are they constant or variable, do they change with the season, with the prevalent and different winds; what is the effect of greater or less quantities of ice in the vicinity?

Third. How may they best be recognized, by the temperature at the surface or below the surface, by soundings, by the character of the bottom, by peculiar forms of vegetable or animal life, by meteorology, by the saltiness of the water?

Fourth. What are the directions and velocities of the currents in this Stream and adjacent to it at the surface, below the surface, and to what variations are they subject? What peculiar arrangements of the currents takes place at the edge of the Stream in passing from the general waters of the ocean into those of the Gulf? Some of these questions will require long-continued observations to solve. If you can obtain something like approximation to the normal condition of the Stream in this summer's work it will be quite satisfactory. Make, then, as many cross sections of the Stream as convenient and as the investigation may show to be necessary. In these sections (1) determine the temperature at the surface and at different depths: (2) the depth of water; (3) the character of the bottom; (4) the direction and velocity of the currents at the surface and at different depths; (5) as far as practicable notice the forms of vegetable and animal life.

Project or note the results as obtained. In the diagram for the temperature at the surface the abscissa will correspond to distance, the ordinates to temperatures, upon a convenient scale arbitrarily assumed. The distance apart at which the observations should be made must depend upon the more or less rapid change of temperature; thus, on the borders of the Stream, they should be more frequent than on either side or within it. The diagrams of the scale of temperature, if made large, will be good guides to the work.

Examine the depth and character of the bottom at the same time. To determine the temperature at a great many depths and at or near the same position, will be difficult and tedious. To avoid the necessity for it, make a complete investigation of the change from the surface to the bottom, at as many points as may appear necessary; thus, for example, make an investigation on the several sections above referred to, on the following lines. Sound before reaching the edge of the stream two lines at or near the edge, two lines within, or as many as appear necessary, two at or near the outer edge and several beyond. As for the lines within the Gulf Stream which are the most interesting, the investigation will show how many will be required. The frequency of the observations in a given depth will be determined by the more or less rapid changes in temperature. Suppose a conjectural diagram to represent the results, the temperature changing rapidly near the surface about a point a, then slowly to a certain depth. A counter cold current being met at b, the change becoming rapid there, this low temperature ranging but slowly toward the bottom at a and b, the observations should be frequent, All the observations on depths and character of the bottom and temperature should be carried quite across the Stream.

It may and probably will turn out that there is a certain depth at which the temperature is invariable for the same position uninfluenced at least by season or by winds, and the assemblage of these points will give a line below the surface constant in direction and velocity, and to determine this will be a valuable practical result.

These sections, with the addition of lines run in the general direction of the Stream, will enable you to represent it on a chart in the usual way, showing the limits and axis, the velocity and direction and temperature at the surface and at any depth which is desirable as that of the line if invariable temperature. As to the character of the bottom, use the Stellwagen Cup and the apparatus which I have requested Lieutenant-Commanding Blake (if he can dispense with it) to send to you at New York. They may both answer the purpose. Characteristic specimens should be preserved, as heretofore, and duly marked with date and position. They will be arranged on your return to the office. The temperature at the surface obtain in the ordinary way or by using the instrument furnished to Commander Gedney last year, and which I shall speak of as the marine thermometer. The velocities and directions of the currents you should ascertain as far as practicable by comparing the positions determined by astronomical observations and by reckoning, by anchoring the vessel or a boat when such a thing is practicable, by the change of position in time of calm. [Observe] The way of the vessel by Massey's Log.  

The existence of a counter current of cold water from the poles below the warm current from the equator has been supposed. This current would produce a position of rest, in which if a heavy body attached to a light one at the surface were immersed, the light one would drift off down the stream of the superior current. If a light body were sent down to the counter current and then detached, it would rise at a point up the stream of the surface current. A boat might be anchored on it by attaching to it a body which would produce a considerable resistance to motion. Two boards put together crosswise would answer the purpose well. It may be that if there is no counter current the velocity near the bottom is so much checked as to cause a variation to be discernible in some such way.

The remainder of the instructions is devoted to details of observation.

Lieutenant Davis made two or three trips into the Gulf Stream, and although the means of observation were tentative on this first year's work, much valuable information was obtained. In 1846 Lieutenant George M. Bache, U.S.N., was detailed to continue the Gulf Stream investigation under practically the same instructions as his predecessor. After a summer's successful work in tracing the temperature across the Stream on three sections, the little vessel was overtaken by a hurricane off the North Carolina coast and Lieutenant Bache and ten of the crew were swept overboard by a sea and lost. The vessel managed to reach port almost a wreck, and the observations, made at such a cost in life, were preserved. Lieutenant Bache gave the name "Cold Wall" to the remarkable change in temperature usually found at what is supposed to be the inner edge of the stream, and he also confirmed the fact that there were alternations of hot and cold water across the stream.  

In the following year the Washington was commanded by Lieutenant S.P. Lee, U.S.N. His instructions contemplated tracing the axis of the Stream, and testing, on his return from the Gulf of Mexico, the existence of the cold wall south of Cape Hatteras. They also called for a resurvey of the section off Cape Henry in order to connect the series of observations made in different years. The observations made by Lieutenant Lee were in the main a confirmation of those of previous years. He found the alternations of hot and cold water, but their positions did not correspond. Lieutenant Bache found a second branch of the Gulf Stream separated by cold water, while Lieutenant Lee found more than one alternation, and the positions of the highest and lowest temperatures were different in the two years.  

In 1848 the work was continued, but with improved means. Two Six's thermometers and two larger on the same plan were used, and also a metallic self-registering thermometer, designed by Mr. Joseph Saxton especially for this work. Instead of a sailing vessel, the U.S. steamer Legare' was commissioned under the command of Lieutenant Richard Bache, U.S.N., and the section off Cape Henry resurveyed and a first examination of the Cape Hatteras section made. The observations of this year furnished data for comparison of the results obtained during three consecutive years on the Cape Henry sections, and were thought to develop the fact that beginning with a minimum at the cold wall, the temperature rises to a maximum in the axis of the Stream, beyond which are two minima and two maxima.  

After the observations above mentioned and until 1853, circumstances connected with the work of the Survey prevented the prosecution of Gulf Stream investigation, but in this year a party under Lieutenant T.A.M. Craven, U.S.N., on board the steamer Corwin, was directed to run four sections across the Stream from Cape Canaveral, St. Augustine, St. Simons Sound, and Charleston, and Lieutenant J.N. Maffitt, U.S.N, on board the schooner Crawford, to run the sections from Charleston, Cape Fear, and Cape Hatteras.  

In addition to copies of the instructions that had been sent to the former officers engaged in the work, Professor Bache also issued detailed instructions as to the special methods of prosecuting the examinations. The axis of the Stream or the point of highest temperature was to be traced by zigzags, by Lieutenant Craven, from Key West to Charleston, and afterwards as far as the latitude of New York, and, with the exception of the latter, which was unavoidably prevented, all the work laid out was most faithfully executed. The soundings taken by both parties were with rope or by Massey's sounding machine, and from the depths obtained they supposed there were two submarine ridges running parallel to the coast. The soundings since taken with pianoforte wire have proved this to have been an error. The temperature curves obtained this year are of the same form as those previously found farther North, and in the duplication of the Cape Hatteras section it was found that the similarity of curve and the positions of the various warm and cold bands were remarkable.  

It was concluded that there were alternations of temperature across the Gulf Stream, the cold water intruding and dividing the warm, making thus alternate streaks or streams of warm and cold water, and it was thought that the observations of Lieutenant Maffitt, on the Charleston and Cape Fear sections, showed a counter current where the cold streaks were found. That such is not always the case will be shown later in discussing the observations of the Blake in recent years. Professor Bache also decided that "the observations of this year have fully proved that in the Charleston section, and those south of it, the bands of cold and warm water are produced by the shape of the bottom of the sea." The progress of the explorations up to 1853 furnished data for the construction of a chart of the Gulf Stream from Cape Canaveral to the section off Sandy Hook, the alternations of temperature being shown by shading, the darker the shade the higher the temperature. (See illustration No. 37.)  

The curves limiting the various bands were not in all cases drawn precisely through the points obtained on the several sections, but in no case but one was the distance from the point actually determined as great as the probable error in the determination of the points themselves. The bands appeared to be invariable in number and position. The supposed axis of the Stream (the highest temperature) was the best determined. The cold wall was the next best to that of the axis, and in the case of the other warm and cold bands the limits of uncertainty in their position at the point of crossing any section were less than half the average distance between the positions in that part of the section.  

In 1854 it was thought to be desirable to continue the examination of the St. Simon's and Canaveral sections in winter for a comparison with the summer's work, and Lieutenant Craven was assigned to the duty. The temperatures obtained showed a remarkable dissimilarity of form from those of the summer. The thermometer at most of the positions was nearly constant from 20 to 100 or 120 fathoms, and below that depth it changed rapidly . At Canaveral the double division of the Stream was shown, but the first maximum was about 7 miles nearer the Cape than in 1853, and the second maximum was warmer. What would generally be taken by navigators as Gulf water was 65 miles from the Cape, "but there had evidently been some great disturbance of temperature just before results were obtained."  

Later in the year Lieutenant Craven investigated the Nantucket section, running a line SE. by S. from the Davis South Shoal light vessel and making observations at about 20-mile intervals for a distance of 230 miles. He found the warmest water at this distance, which was 40 or 50 miles farther south and east in October, 1854, than it was in August, 1845. The alternations of warm and cold water were discernible, but, as in the case of the warmest, they were a greater distance off shore. In 1855 the work of research was continued, Lieutenant Craven running a section off Cape Florida in May, and Lieutenant Sands along the axis of the Stream in June, and also a section off Nantucket in October. The section off Cape Florida was completed successfully and the axis of the Stream followed as far as Cape Lookout, but in the attempt to finish the Nantucket section only the warm water of the axis was reached. In 1857 a number of interesting observations were added to the Gulf Stream exploration. A section was run from Havana to Sand Key, Florida, the inner edge of the Stream was traced from Cape Canaveral to Cape Fear, the axis was traced from Tortugas to Cape Hatteras, and a line was run from Halifax in the direction of Bermuda. It was unfortunate, however, that the thermometers were not always in working order, as many temperature observations on both the Havana and the Halifax lines had to be discarded. During the next three years the work was chiefly confined to investigating the temperatures across the Straits of Florida.  

Although the plan for the exploration of the Stream contemplated the determination of the density of the water and the direction and velocity of the currents, the actual work performed was the determination of temperature and depth. The existence of a polar current underlying and running counter to the Gulf Stream was assumed by Professor Bache, the assumption being founded mainly upon theoretical considerations, and not on actual current observations. Generally the only record of current was obtained by the difference between the dead reckoning and the astronomical positions of the vessels, as, for example, in the record of observations of one party it says:  
 

August 16.--A comparison of the afternoon with the morning sights for chronometer show a current of 5 miles eastwardly. The vessel was lying-to in the interval. The meridian observations showed a northerly current during the last 24 hours.


Another record was:
 

August 18.--Tried the current with a boat anchored with 1,200 fathoms line (no bottom). Found it on the surface setting SW. by W. 0.29 mile per hour. At 25 fathoms depth, SSW., same velocity. This agrees with chronometer sights of morning and evening, the brig lying-to all day and drifting a little to the west with the sea. The instruments employed in the investigation under Professor Bache were of the most approved patterns, were handled with the greatest care, and every observation scrutinized closely, but the difficulties against which they had to contend rendered the work very laborious and the results sometimes liable to doubt, which necessitated discarding the observation.  

The thermometers were as follows: The self-registering instruments of Dr. Rutherford, of Edinburgh, and Six, of Canterbury; a metallic thermometer made by Breguet, of Paris, and another by Mr. Saxton, of the Coast Survey Office. Rutherford's is a minimum thermometer, the cohesion of the spirit drawing an enamel index to the lowest point reached by the contraction where it is left as the fluid expands. To render it applicable to deepsea temperatures it is inclosed in a glass globe made strong enough to withstand moderate pressures. In use it is necessary to keep the tube horizontal, which is not always possible. In using rope, too, for lowering, the centrifugal motion caused by the twisting or untwisting of the rope prevents accuracy or certainty of registration.  

Six's thermometer is composed of a bent tube of glass, one of the branches terminating in a large expansion to form a cylindrical chamber and the other only slightly enlarged at the end. The lower part of the tube contains mercury, which partly fills both branches on either side of the bend. The upper part of each branch including the chambers, is filled with highly rectified spirits of wine. A rise or fall of temperature will cause a greater expansion or contraction of the spirits in the larger end than in the smaller, which will cause the column of mercury in that branch to rise and fall, and thus a motion is communicated to its surface in both branches. A small index of steel, coated with glass and lightly held in place by a delicate spring, is pushed along by the surface of the mercury and remains at the farthest position where the mercury withdraws.  

The Breguet metallic thermometer is constructed on the principle of the unequal expansion of metals. The compound bar is composed of laminae of brass and steel united together and bent into horseshoe form. One end is firmly fixed and the other, being free to move under the influence of the unequal expansion or concentration of the two metals, gives rotary motion to an index and registers on a dial by means of an auxiliary hand held by friction at the highest or lowest point of temperature. The hole is inclosed in a brass case made sufficiently strong to withstand pressure.

Saxton's thermometer is the same as the Breguet in principle, but the laminae are composed of silver and platinum and wound in a spiral instead of being bent into horseshoe form. It is heavily gilded and inclosed in a metal case, into which the sea water is admitted. According to our ideas at the present day these instruments were faulty.

The conclusions adopted by Professor Bache from the observations taken under his direction between 1854 and 1860 were as follows: That between Cape Florida and New York the Gulf Stream is divided into several bands of higher and lower temperatures of which the axis is the warmest, the temperature falling rapidly inshore and more slowly outside. This is not only the case at the surface, but, with modifications was easily understood, at considerable depths. That between the coast and the stream there is a fall in temperature so abrupt that it has been aptly called the "Cold wall." The cold wall extends, with varying dimensions and changes of its peculiar features, along the coast from Cape Florida northward as far as examined. Inside this wall of marked colder temperature there is another increase, while outside the warmest band, which is next the cold wall, there is another warm and one other cold band. The distance these are situated from the coast are shown in the following table:  (image not available)

In the sections on which the work was duplicated, viz, the Cape Henry and the Cape Hatteras sections, the positions of the cold wall and axis of the Stream agreed within 51/2 miles, and those of the succeeding points of maximum and minimum temperature within 71/2 miles.

After the year 1860 Gulf Stream investigation ceased almost entirely until 1867, when Prof. Henry Mitchell of the Coast Survey sounded between Key West and Havana and observed the currents to the depth of 600 fathoms, the deepest ever attempted to that date. The method adopted to observe these currents was the following: Two globes or cans of equal surface were attached to each other by a line of the desired length. One of the globes was loaded so as to sink to the length of the connecting line, while the other was on the surface supporting its mate. Within the latter was a light reel upon which a small log line, passing through an aperture, was wound by a crank from without. To the end of the line was secured a third globe floating freely upon the surface of the water. When making an observation the log line was reeled until the surface globes were together. At a signal the reel was released, and, if the currents influencing the two were different, the amount of separation in a given time indicated the relative velocities.  

A trail was made of surface currents and at 300 and 400 fathoms depth, at a station 3.7 miles from Fort Chorrera, Cuba, and a velocity of about one knot was found at each. Another trial was made about 3 miles farther off shore, with the result, that at 600 fathoms depth the current was about 10 per cent less than on the surface. From these experiments, Professor Mitchell was led to conclude that "the Gulf Stream has a nearly uniform velocity and constant course for a depth of 600 fathoms, although its temperature varies in this depth 40oF." In the following year Professor Mitchell continued current observations in the Santaren and St Nicholas Channels, using an anchored buoy for the initial point from which to start the float for service observations. His conclusion was that the water in these channels was motionless.  

In 1868-'69-'70 expeditions were fitted out by the British Admiralty, and, under the scientific direction of Dr. William B. Carpenter, Mr. J. Gwyn Jeffreys and Prof C. Wyville Thomson, sounded and dredged off the coast of Europe from the Faroe Islands to Gibraltar. Accurate temperature observations were taken, and from these Professor Thomson has given the course of the currents in what is called the northeastern extension of the Gulf Stream. By the term Gulf Stream he explains:  

I mean that mass of heated water which pours from the Straits of Florida across the North Atlantic and like wise a wider but less defined warm current, evidently forming part of the same great movement of water, which curves northward, to the eastward of the West Indian Islands. I am myself inclined, without hesitations, to regard this stream as simply the reflux of the equatorial current, added to, no doubt, during its northeasterly course by the surface drift of the anti-trades which follow in the main in the same direction.

Of the course of the Gulf Stream he says: "It seems to me that the Gulf Stream is the one natural phenomenon on the surface of the earth whose origin and principal cause, the drift of the trade winds, can be most clearly and easily traced." He concludes that the Stream enters the North Atlantic and accumulates. Finding no free passage toward the northeast, a portion of it goes toward the Azores, but the accumulation to the northward forces a return eddy current to underrun certain portions of the warmer flow.
 

In 1873, the Challenger expedition, under the command of Captain Sir George Nares, R.N., with a full staff of scientific gentlemen, of which Professor C. Wyville Thomson was the head, added some most valuable data to the record of Gulf Stream investigation. They crossed the North Atlantic twice, and made passages north and south along the shores of both hemispheres, making the most accurate observations of temperature and specific gravity. In the passage of the Challenger across the Gulf Stream off New York, and between Halifax and Bermuda, the alternations of warm and cold water were found. They also at times made observations of the strength and direction of the currents, both surface and subsurface, using practically the same method as that employed by Professor Mitchell in the Straits of Florida in 1867.  

The Coast Survey continued its examination in the Gulf Stream in sounding and dredging during the years 1868 to 1878, with the steamers Bibb, under Acting Master Robert Platt, U.S.N., the Bache, under Commander J.A. Howell, U.S.N., and the Blake, under Lieutenant Commander C.D. Sigsbee, U.S.N. Mr. L.F. Pourtales and Professor Louis Agassiz accompanied the vessels at different times for the purpose of collecting and arranging the results of the dredging operations. In 1879 the investigation was extended into the Caribbean, and a theory advanced as to the flow of its waters by Commander John R. Bartlett, U.S.N. who commanded the vessel.  

In his report accompanying the record of the season's work he concludes that the equatorial current, which sets directly against the Windward Islands, is by them and their connecting ridges deflected northward, and so following their outer edge passes around the Virgin Islands to the westward and through the deep channel to the northward of San Domingo. He suggests, also that on reaching Cuba the current divides, a part flowing northwest through the old Bahama Channel and a part through the Windward passage between Cuba and San Domingo, and thus by Cape San Antonio into the Gulf of Mexico. His report states that the specimens of bottom taken in the Windward passage give evidence that the current moves in depths greater than 800 fathoms and that it reaches the bottom. He remarked, too: "The current, always found flowing north along the eastern side of South America, on reaching the island of Tobago divides, part joining the equatorial current setting north along the chain of Islands, the remainder following the coast line of Trinidad and the Spanish Main, and so around the entire circumference of the Caribbean Sea, finding at last an outlet at the Mona Passage and the Anegada Channel to join the equatorial current on its way to the Gulf of Mexico." This circulation is so contrary to that found in the later investigation made by the Blake that it is given in full. Professor Alexander Agassiz accompanied Commander Bartlett on this cruise, and while he quotes that latter on this subject he does not seem to adopt these ideas without question, for he says: "In the present state of our knowledge it is difficult to trace the path of the equatorial water as it is forced into the eastern Caribbean."  

In 1877 the first attempt was made by the U.S. Coast Survey to systematically observe ocean currents from a vessel anchored at sea. The schooner Drift was built for this purpose, and under command of Acting Master Robert Platt, U.S.N., successfully observed the currents between Nantucket and Nova Scotia, occupying eight stations for varying periods, the longest time being over 90 hours and the greatest depth of water 135 fathoms.  

The first reliable soundings which developed the bed of the Gulf Stream from the Straits of Florida to George's Bank were made by Commander Bartlett in 1881 and 1882. It will be remembered that the soundings by Lieutenants Davis, Lee, Craven, and others before 1860 were made with rope or registering devices, such as Massey's, and when these are used in a strong current or in considerable depths they are unreliable. Commander Howell, when in command of the Coast Survey steamer Bache, was provided with one of the Thomson wire sounding-machines, which had been so successfully used by Captain Belknap on board the U.S.S. Tuscarora in the Pacific. The principle of sounding with piano-forte wire was much improved by his successor, Lieutenant-Commander Sigsbee, so that any depth could be ascertained with certainty and accuracy in almost any weather, and since that time the Blake has used nothing else for the purpose.  

Commander Bartlett ran lines about normal to the coast at intervals of 60 miles from Jupiter Inlet North. He says:  

Instead of a deep channel which had previously been reported, our soundings show an extensive and nearly level plateau extending from a point to the eastward of the Bahama Banks to Cape Hatteras. Off Cape Canaveral it is nearly 200 miles wide, and gradually decreases in width to the northward until reaching Hatteras, where a depth of more than 1,000 fathoms is found 30 miles off the shore. This plateau has a general depth of 400 fathoms, suddenly dropping on its eastern edge to 2,000 fathoms. The soundings in the strength of the current were all taken with a 60-pound shot, the time allowed for the sinker to reach the bottom being less than one minute to each 100 fathoms in depth.


In the lines crossing the Stream from Nantucket to Bermuda and returning to Cape Hatteras, Commander Bartlett took serial temperatures at short intervals and surface observations every mile. He says:  

In regard to the results of the investigation of this last season's work, I have been particularly interested in what I was expected to find--that is, the bifurcation of the stream into warm and cold bands. The warm and cold bands have been accepted for so long a time as a fact and have been reported by such reliable authorities that there must have been conditions of weather during our observations. I have already stated that our observations did not indicate anything of the kind.
In 1883 Lieutenant J.C. Fremont, Jr., U.S.N., in command of the schooner Drift, was detailed for the first Gulf Stream current investigation to be made from a vessel at anchor. The vessel was supplied with 700 fathoms of galvanized wire rope three-quarters of an inch in diameter, and instructions issued to observe current at various places near the 100 fathom curve along the Coast, and also in the stream between Jupiter Inlet and Memory Rock. The Drift is a small deep-draft schooner of about 100 tons. Not being fitted with a steam windlass, the rope, which was coiled on deck, was veered and hove in by hand. In spite of this, Lieutenant Fremont succeeded in occupying five stations across the channel, the deepest anchorage being over 400 fathoms. The currents were observed by floating cans attached to a log line. It was discovered that, "contrary to expectation, the greatest velocity was not found at the supposed center of the stream, but somewhat to the westward of it. The greatest velocity noted was 4.7 knots in latitude 27o05' north and longitude 79o44' west. The depth here was only 190 fathoms, the distance west from the supposed axis 10 miles, and from the Florida coast about 20 miles."  

Before beginning the description of the Blake's examination of the Gulf Stream under my command there is one other investigation to which allusion should be made. His Highness the Prince of Monaco during the past years has been engaged in scientific researches on the coast of France. The object of his examination was primarily for the purpose of discovering the cause of the departure of the sardines from the Bay of Biscay; but in connection with this he has devoted much of his time to a study of the eastern portion of the Gulf Stream. In order to discover the velocity and direction of this current he adopted the method of floats, but carried it out in a manner and magnitude never before attempted. His floats were barrels and bottles to a limited number, but mostly were specially constructed copper globes, and all were ballasted so as to expose as little surface as possible to the wind and waves. The ballast of the barrels and globes was suspended several feet below the surface of the water, and so arranged that by the time the float accumulated a quantity of material (barnacles, grass, etc.) the ballast would become detached.  

He put overboard from his yacht no less than one thousand six hundred and seventy-five of these floats. In 1885, one hundred and thirty-nine in a distance 170 miles northwest of Azores. In 1886, over five hundred more were placed along the twentieth meridian off the coast of France. In 1887, nine hundred and thirty-one were set adrift between the Azores and Newfoundland, and afterwards another line farther to the northward and eastward in the region of the supposed northeast extension of the stream near the fiftieth parallel. Dividing each of the lines into thirds for purposes of study, he found that most of the floats traveling to the southward came from the southward and middle groups, and of those going to the northward and eastward most of them belonged to the northern groups, but there were some from each group which had traveled in the opposite directions. Of those placed between the Azores and Newfoundland, one from near the northern end of the line and one from near the middle were found in Ireland, others from near the same points traveled to the coast of Norway, and more were distributed along the shores of France, Spain, and Africa. None of those started near the Azores were found north of Lisbon. Two of those from the northern end of the line off the coast of France found their way to the West Indies.

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