# Narrative of a Voyage Round the World (Belcher)/Volume 1/Hydrographic Instructions

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HYDROGRAPHIC INSTRUCTIONS
for
CAPTAIN BEECHEY,
subsequently for
CAPTAIN BELCHER.
The general objects of the expedition which has been placed under your command having been set forth in their Lordships' orders, it becomes my duty to enter somewhat more diffusely into the nature and details of the service which you are to perform.
The first point to which your orders advert after quitting England is the Eight Stones. You will probably add one more to the many testimonies which have been already collected of their non-existence, at least in the position assigned to them in the old charts; but before we venture to expunge them it would be satisfactory to make all the inquiry in your power at Madeira, respecting the traditions on which their existence is asserted.
In approaching the coast of Brazil, you will have a good opportunity of verifying or discarding the bank of ​soundings which has been adopted in our charts, from a circumstantial account in the remark-book of the Fly, within a week after her leaving Bahia, and with chronometer on board. For this purpose it will be proper to run down the parallel of 16° 50 S, (or 16° 55, so as to allow for the northerly current,) and to carry in a chain of deep sea soundings from about the longitude of 35° 30 W., till in 37° 30 W. From thence you may shape an extremely useful course, so as to round Cape St. Thomé and Frio at such a distance, if the wind will permit, as will enable you to intersect some very discordant soundings which have been inserted in the chart, from different but apparently good authorities. One well determined line of genuine depths Avill go far to elucidate all the difficulties.
At Rio de Janeiro, or at Santa Catharina, you will have an important task to perform, and the choice of the two places is of no moment, provided the chronometers enable you to determine their meridian distance with precision. The longitude of the former has been reduced within very narrow limits, by various observers, and a vast number of observations of various kinds, the mean of which gives 43° 8 W., for the little island of Villegagnon; but as every change of a standard meridian is attended with great inconvenience to seamen, it may be hoped that a good series of moon-culminating stars may now put the question at rest, so that no further alteration will be requisite, at least for nautical purposes.
As magnetic phenomena are objects of much scientific interest at present, you should not lose the opportunity of obtaining some careful observations of dip and intensity, at one of the above places, and likewise at one of the high southern positions where it was obtained by Captain P. King. Port Famine would be well adapted to the purpose ​if other circumstances should not render that route inconvenient, and the more so as it was the standard meridian to which he referred all the longitudes of his survey.
From thence there will be nothing to delay your progress towards that part of the western coast where Captain Fitzroy's late survey terminated. Unfortunately no account of his concluding operations has yet arrived, but by a comparison of dates it does not appear that there could have been time to examine much of the coast of Chili, to the northward of Valparaiso, or even to complete it down to that port. This question must be decided, because at no great distance to the southward lie the shoals of Topocalmo, where an American ship was wrecked, and which, if they have not been satisfactorily laid down by him, and their connexion with the shore examined, must not be neglected by you.
It is, however, probable that at Valparaiso you will be able to obtain such information on that subject, as may help to guide your movements; but if not, there will be little danger of repeating any part of his work if you commence yours at Coquimbo, leaving the interval to be hereafter effected, when the return of the Beagle, or the arrival of her despatches, shall enable me to define more exactly the point at which the great work assigned to you by their Lordships ought to begin.
Of that extensive region which your work is to comprehend, we are at present best acquainted with the southern portion, including Chili and Peru. Yet of those long and populous coasts, excepting the ports of Guayaquil and Callao, our whole knowledge is derived from two Spanish charts, on the limited scale of one inch to twenty-eight miles ; and it appears from Captain Fitzroy's recent examination of the large island of Chiloe, and of the intricate gulf of Chonos, that those charts ​arc evidently the result of mere running of surveys. The half-knowledge to be obtained by this kind of survey, has always acted as a check on the advance of geographical and nautical information, and is in itself useless; for the native coaster wants nothing beyond his local experience; the regular foreign trade employs a pilot; and the occasional visitor sees that all the details are so unlike the truth, that he does not even attempt to correct;—and thus our enterprising carriers in peace, and our active cruizers in war, find themselves equally foiled in their operations along shore. These evils can be remedied only by correct charts, on scales appropriate to the greater or less intricacy of their contents, and showing the true shape and nature of the shore, the positions of the towns, the places for anchoring, the depths on the bank, and the appearance of the land, as it makes in the offing. The present state of science, and the excellence of modern instruments, afford ample means for acquiring this knowledge with comparative facility, and our western American commerce has long been in need of such charts; but especially now, that the impulse it has received from the revolutions of those rich but only half maritime countries, has brought our vessels into contact with every port from Valdivia to the Columbia.
In carrying this great survey into effect, their Lordships have placed the fullest reliance on the unabated zeal and talents which you have heretofore displayed, and they have cautiously and wisely abstained, in your orders, from fettering you in the selection of your ground, or in that division and disposition of your time, which the periodic changes of season, or the occasional necessities of the vessels, may require. If, therefore. Providence permits you to preserve your resources unimpaired, and if the several governments interpose no obstacles, you ​will, doubtless, pursue this important work, with all the energy in your power, and with all the perseverance consistent with a due regard to the health of your officers and crews.
Where their Lordships have placed such unlimited confidence, it would ill become me to enter too minutely into the lesser pursuits, which are connected with the main object of the coast line ; but there are some detached islands and dangers to which it is proper to advert, and to which it is necessary to call your attention. In crossing from one division of the survey to the other, you might visit and determine the position of the little islands of St. Felix; for though they can offer neither resources nor shelter, yet such insulated specks in the ocean are often useful to the mariner in rectifying his longitude.
A little further to the westward, the brig Cannon, in 1827, discovered a dangerous reef, of half a mile in length, which she called the London Bank, and placed in 27" 6 south, and 92" 16 west, and which it would be useful to verify.
If there be any truth in the report that the earthquake of February has considerably shaken the island of Juan Fernandez, it might be useful to stretch over there, and to examine if any material change has really taken place in the anchorage. Some other extraordinary effects of this earthquake are said to have occurred on the coast of Chili, in permanently elevating part of the shore, and in changing the depth of the adjacent sea. These assertions, if at all true, are probably exaggerated, and you will render a service to geology, by minutely inquiring into the circumstances, and communicating the result without delay.
It may be hoped that Captain Fitzroy has sufficiently ​examined the Galapagos, and therefore, till that is ascertained, your time should not be occupied there.
Cocos Island is stated by Vancouver to be only four miles in length, while, according to Collnet, it is not less than four leagues; and its position being also imperfectly known, it should be visited. The little solitary islet of Malpelo should likewise be definitively placed. The islands of Revilla, Gigado, &c., will naturally be included in your general chart of California.
Further off, in 16° North, and about 130° West, a large group of coral islands is supposed to have been seen. It is not probable that you will have to stand so far out in any of your traverses, but if accident should lead you near them, it will be proper to establish their position, and to ascertain their general character.
Political circumstances have invested the Columbia river with so much importance, that it will be well to devote some time to its bar and channels of approach, as well as to its inner anchorages and shores.
In touching at some of the points of Vancouver's survey, you will perceive, that unless in any cases of gross error, it is not their Lordships' intention that you should do more than rectify the general longitudes in the chart of that officer, as they are probably quite adequate to any interest that is felt at present about that archipelago of islands. If, however, you have a convenient opportunity, it will be desirable to ascertain whether there is not a broad sea passage through his King George Island, dividing it into two islands.
As the terminal point of your whole survey to the northward, the magnificent mountain of St. Elias may be named; and its exact position and height should therefore be determined.
Next in importance to the accuracy of the coast line ​and of the shoals, is the precision and fulness of the soundings, with the quality of the bottom. There can be no doubt that the nature of the substances which are spread over the bottom of the sea does not depend on mere chance, but that they are in some measure connected with the adjacent shores, and sometimes with those of more distant parts of the coast, from which they have been swept by currents; and it would be a great benefit to navigation if this relationship could be satisfactorily traced. The transition also from one species of sand to another, and the link by which these beds or patches are connected, are subjects which would be well deserving the reflection and exertions of our scientific mariners. Besides the soundings to be carried along shore, (the breadth of which zone, proceeding from the back of the rollers, will depend on their depth and regularity,) the outer edge of the bank should also be laid down, as being a most important aid to the navigator, and a sufficient number of depths marked in the intervening space, to show the general slope of the bank. This outer edge may be assumed at a hundred fathoms, as in general it rapidly sinks from that depth, to one beyond the usual reach of the lead. Massey's machine should not be used in a greater depth than fifty or sixty fathoms.
In approaching the several groups of islands, and in the various runs which either vessel may have to make in the course of the survey, at a distance from the land, no opportunity should be missed of throwing down the deep sea lead. The negative language of no bottom soundings on the charts, is next in value to the real depth; and, unless when pressed in time by some paramount object, it should be the established practice of a surveying vessel, both night and day, though apparently ​remote from any bank, to have a deep cast of the lead every ten or twenty miles, according to the distance from the shore. This might sometimes lead to useful discoveries; and in order to abridge the labour, as well as to prevent the unwholesome effect of wet sleeves, the sounding which should be always employed on these occasions. No consistent account of the currents along the western American coast has been yet framed, though in no part of the world would it be of more importance and value. Observations, therefore, to determine the direction and strength of the current, should not be left to be inferred from the mere error of the dead reckoning, when traversing the sea in the offing, nor to the casual set of the boats when employed in-shore, but should be systematically made, for the express purpose of forming a general view ol this interesting subject, and which can only be effected by a great accumulation of data.
In applying this rule to the extensive ocean which will be more than once traversed by the present expedition, it may be as well to divide the inquiry into distinct questions.
1. The actual set and direction of the current in all parts that the vessels may visit.
2. Are the currents permanent, or in what degree are they modified by the daily sea and land breeze, or by the periodic monsoon, or by the issue of the large rivers?
3. To what distance does the regular current extend from the coast? and where do the neutral space and counter-current begin?
4. Is the general direction of the permanent current parallel to the shore, or oblique?
5. To what depth do these currents extend downwards?
The comparative temperature of the atmosphere and ​the sea whenever the current runs from the northward or southward, should be continually observed, and marked in the log. A series of such observations would show under what circumstances the thermometer will indicate the effect of currents.
A minute examination of the tides, including all those data by which they may be accurately calculated, their local set, and the extent to which they are influenced by the periodic winds, and by the sea currents, arc so evident a part of your survey that it need not be dwelt on here. When practicable, their extreme height at the springs should be referred to a fixed object on the shore.
You will be furnished with a scale by which the force of the wind is to be expressed, and certain abbreviations by which the weather may be correctly described, and these are invariably to be employed in marking the logboard and log-books of both vessels.
The periods and limits of the trade winds, monsoons, and rains, will no doubt be a constant object of your study. It is true that your observations of them must be confined to the place where your vessels are; but still you will be able to collect a large number of accurate facts; you may perhaps pick up some authentic information from others; your journals of the Blossom and those of former navigators, will supply many connecting circumstances; and I feel confident that on your return home you will present to their Lordships the first consistent account of this interesting subject. Hitherto the practical seaman knows not where to seek for the periods of change, which are so essential to the due performance of his voyage; and those who would investigate and generalise the laws of these curious phenomena cannot find any distinct statements on which they can rely.
​No possible pains should be spared which may throw any light on the hitherto inexplicable form of" the curves which unite the degrees of equal magnetic variation, or on the annual motion of those curves to the east or to the west.
The diurnal arcs of variation should also occupy your attention in favourable situations ; and it will be very interesting, if, by multiplying observations, you can either confirm or refute the assertion that there is a constant difference between the variation on the east and west sides of an island, independent of that due to the space it occupies. The restrictions under which these delicate observations should be made will readily suggest themselves to you. No subject can be of greater importance to navigators than the laws which affect their compass, and none should be pursued with more perseverance; azimuths and amplitudes should be obtained every day, and under every variety of circumstance, as well on shore as on board ; and the latter, whenever practicable, should be made with the ship's head either north or south, or rather on the line of no deviation, as shown by the table which will have been formed in each vessel, of her local attraction.
The local attraction, however, varies in the ratio of the dip; it should, therefore, be carefully retried, (on every point of the compass,) at both extremes of the survey, as well as near the equator, and a full report of each trial transmitted to this office.
Observations for the dip and intensity should be made at different points of the coast, carefully avoiding the neighbourhood of any place which may be likely to influence the needle.
Nautical descriptions of the places comprised within the limits of the Survey, and clear directions for the ​ports and dangers, adapted to all classes of seamen, will obviously be among the essential parts of the survey; but there will also be opportunities of collecting auxiliary information which, when digested, may be made extensively useful to those who may have to visit that coast;—such as places of refuge after any disaster at sea; ports where pilots are requisite; the most advantageous methods of obtaining water, wood, and other supplies; the general resources and productions on which vessels may depend; the usual effects of the climate in the rainy and in the dry seasons; and notice should be given of those spots which are peculiarly unhealthy. In short, no facts can be useless in compiling directions hereafter.
It has been suggested by some geologists that the coral insect, instead of raising its superstructure directly from the bottom of the sea, works only on the summits of submarine mountains, which have been projected upwards by volcanic action. They account, therefore, for the basin-like form so generally observed in coral islands, by supposing that they insist on the circular lip of extinct volcanic craters.
In order, by a satifactory experiment, to bring this question to a direct issue, their Lordships have ordered you to be supplied with a complete set of the boring- apparatus used by miners; leaving it to your own judgment to select any coral island which may be well adapted to the purpose, and which will lead you as little as possible from the line of your survey. They wish you to fix upon a convenient spot of the island where the operation cannot be disturbed by the surf, and there to bore perpendicularly, so as to perforate the whole thickness of the coral, and to enter the tool ​sufficiently deep in the rock on which it is based to furnish specimens for future analysis. You will of course keep a register of the contents of the auger every time it is withdrawn, and if the structure or density of the coral appear to change, it will be desirable to have a series of such specimens also preserved, and tallied with their corresponding depths.
Immediately that the bore hole arrives at its greatest depth, provided no water has been allowed to enter, it will be well to contrive some method of sending down a registering thermometer, so as to ascertain the temperature of the bottom of the hole.
Hitherto it has been made a part of the duty of all the surveying vessels to keep an exact register of the height of the barometer, at its two maxima of nine, and its two minima of three o'clock, as well as that of the thermometer at the above periods, and at its own day and night maximum and minimum, as well as the continual comparative temperature of the sea and air. This was done with the view of providing authentic data, from all parts of the world, for the use of future labourers in meteorology, whenever some powerful mind should happily rescue that science from its present neglected state. But those hours of entry interfere so much with the employments of such officers as are capable of registering those instruments with the precision and delicacy which alone can render these data useful, that I do not think these journals should be further required. The daily height of the former, and the extremes of the thermometer, will be sufficient to record, unless from some unforeseen cause you should be long detained in any one port; a system of these observations might then be advantageously undertaken.
​There are, however, some occasional observations which cannot fail of being extensively useful in future investigations.
1. During the approach of the periodic changes of wind and weather ; in which case the hygrometer also should find a place in the journal.
2. The mean temperature of the sea at the equator, and under a vertical sun. These observations should be repeated whenever the ship is in either of those situations, as well in the Atlantic as in the Pacific; they should be made far away from the influence of the land, and at certain constant depths, suppose fifty and ten fathoms, and at the surface, and the latter ought to be again observed at the corresponding hour of the night.
3. A collection of good observations systematically continued, for the purpose of connecting the isothermal lines of the globe, and made as above at certain uniform depths.
4. Some very interesting facts might result from a comparison of the direct heat of the solar rays in high and low latitudes. The two thermometers for this purpose should be precisely similar in every respect; the ball of the one should be covered with white kerseymere, and of the other with black kerseymere, and they should be suspended far out of the reach of any reflected heat from the ship, and always at the same elevation above the surface of the water; the observations should be made out of sight of land, in a variety of latitudes, and at different hours of the day, and every pains taken to render them all strictly similar and comparative.
5. All your meteorologic instruments should early in the voyage be carefully compared throughout a large extent of the scales, and tabulated, for the purpose of ​applying the requisite corrections when necessary, and one or more of them should be compared with the standard instruments at the Royal Society or Royal Observatory on your return home.
6. All observations which involve the comparison of minute differences, should be the mean result of at least three readings, and should be as much as possible the province of the same individual observer.
7. In some of those singularly heavy showers which occur in crossing the equator, and also at the changes of the monsoon, an attempt should be made to measure the quantity of rain that falls in a given time. A very rude instrument, if properly placed, will answer this purpose; merely a wide superficial basin to receive the rain, and to deliver it into a pipe whose diameter, compared with that of the basin, will show the number of inches, &c., that have fallen, on an exaggerated scale.
8. It is unnecessary to call your attention to the necessity of recording every circumstance connected with those highly interesting phenomena—the Aurora Australis and Borealis; such as the angular bearing and elevation of the point of corruscation; the bearing also of the principal luminous arches, &c. &c.
9. It has been asserted that lunar and solar halos are not always exactly circular; and a general order might therefore be given to the officer of the watch to measure their vertical and horizontal diameters whenever they occur.
Large collections of natural history cannot be expected, nor any connected account of the structure or geological arrangement of the great continent which you are to coast; nor indeed would minute inquiries on these subjects be at all consistent with the true objects of the survey. But at the islands, and even along the ​coast, to an observant eye, some facts will unavoidably present themselves, which will be well worth recording, and the medical officers of both vessels will no doubt be anxious to contribute their share to the scientific character of the Survey.
F.B.
19th December, 1835.
INSTRUCTIONS
to
CAPTAIN BEECHEY,
subsequently to
COMMANDER E. BELCHER.
By the Commissioners for executing the office of Lord High-Admiral of the United Kingdom of Great Britain and Ireland, &c.
You are hereby required and directed to take the Starling, surveying vessel, under your command, (the lieutenant commanding her being directed to follow your orders,) and the Sulphur and Starling being in all respects ready, you are to put to sea and to proceed with her to Plymouth Sound, for two chronometers which have been selected for you there, and having determined your chronometric departure from the west end of the breakwater, you are to make the best of your way to the ​supposed place of the Eight Stones, and crossing the parallel of 34° 45 north, in the longitude of 16° West, you are to spread the Starling to the westward, according to the clearness of the weather, so as to make sure of discovering any broken or discoloured water in the interval between the two vessels.
You are also to get a few deep casts of the lead, when passing the alleged place of that shoal.
You are then to repair to Madeira, to verify the rates of the chronometers by the standard meridian of Funchal, or if that be impractible from the state of the weather, you are to proceed to Teneriffe for this purpose.
Every exertion is then to be made to cross over to America with the least possible delay, and to approach it on the parallel of 16° 55 south, in order to fix the outer limit of the Abrothos Bank. In that latitude you should carry on a series of sea-bottom soundings from 35½° west, till you have arrived fairly on the main bank, or in 37° 30 west, when, crossing the banks to the southwards, with a line of soundings, you are to proceed to Rio de Janeiro.
At that place you will not only obtain satisfactory ratio of the chronometers, but by setting up the transit instruments, a few nights 'observations of moon-culminating stars, will enable you, it may be hoped, to settle finally its longitude.
If, however, the moon should there be unfavourable, the same object may be equally well obtained at Santa Catharina. The coast, between these two places, has been sufficiently surveyed by Le Baron Roussin, but their meridian distance requires confirmation, and your means are fully capable of dispelling all further uncertainty.
From Santa Catharina, you are to pass forward towards the passage between the Falkland Islands and ​the Main, and taking nearly the mid-channel, you are to sound freely between the latitudes of 50° and 53° S., there being good grounds for believing that the bank which unites that group of islands to the continent, is within the reach of the deep-sea lead.
You are then to round Cape Horn, or proceed by the Strait of Magellan, as you may find most eligible, and to make the best of your way to Conception, up to which place it may be supposed that Captain Fitz-Roy has fully completed his survey, although he may possibly have carried it as far as Valparaiso.
This point, however, can be easily ascertained at one of those ports, and from wherever it may appear to have been terminated, you will forthwith begin the great work which has been confided to you by us; or if there should be any doubt about the limits of Captain Fitz-Roy's labours, you may safely commence at Coquimbo, beyond which, in the time consumed by the Beagle, they could scarcely have extended.
When Captain Fitz-Roy's missing despatches arrive, that point will be communicated to you; and if any part of the above interval should not have been examined, and particularly the dangerous banks off Topocalmo, you can easily resume your operations to the southward, so as to include them.
As Rio de Janeiro may be considered the standard point to which it is so convenient to refer the meridian distances obtained on the eastern side of America, so there should be a similar point on the coast of Chili. The choice of that station we leave to you, and there you will again establish the transit instrument, and determine the difference of longitude from Greenwich.
The extent of coasts along the western side of America ​is so great that the utmost energy will be requisite in conducting the necessary observations, and can be effected in any reasonable time only, by skilfully combining them with the changes of seasons which take place at alternate periods of the year to the north and south of the Equator. On the approach, therefore, of the monsoon to the coast of Peru, you are to make the utmost expedition in removing both vessels to California, where San Francisco offers a healthy and convenient spot for fresh rating the chronometers.
Little is known of this great country except that it is rapidly increasing in population and commerce; and as it contains but kw harbours, its shores steep, and the approaches bold, there will be little motive for detention between San Francisco and the district visited by Captain Vancouver.
You will then have an excellent opportunity of verifying the longitudes of two or three of the above officer's principal points, which differ materially from those which Senor Quadra and the Spaniards have assigned to them, and on which therefore depends the whole form of that coast.
From this region you will again pursue the survey to the southward along to the shores of Guatemala and Mexico, and so on, alternately changing your ground according to the periodic change of weather, till in a succeeding season you will have met the operations proceeding to the northward. With the very dubious knowledge which exists of the periods of the winds, or of the changes of wet and dry weather, which prevail along the great continent, and the still less knowledge of the character of the shores, which will in some places delay, and in others rapidly accelerate your progress, it is impossible ​to determine beforehand the extent of survey, either to the north or south, which you should perform in the alternate seasons. This division of your labours must be entrusted to your own zeal and prudence, but founded on the one leading principle, that on those parts of the coast which are uninhabited, where no ports or anchorages can ever invite the activity of commerce, and where bold and straight shores offer no difficulties or dangers to the passing navigator, there no precious time should be wasted, or minute accuracy employed, which would be as uninteresting to the geographer as useless to the seaman.
When obliged to stand far out to sea, in order to reach the remote divisions of the survey, you are to make that passage as useful as possible, by the selection of new ground, or by rapidly crossing the curves of magnetic variation, or by searching for some of the many islands or dangers with which different navigators have studded the Pacific ocean, and which in numerous cases will probably be found to originate in three or four erroneous positions having been given to the same spots.
On most parts of the coast you will be able to obtain fresh beef, flour, cocoa, and other victuals and refreshments; and if you should want a further supply of salt provisions or of stores, you should apply to the senior officer of the squadron on the western side of America, who will be directed to assist you.
You are to attend to the instructions and suggestions contained in a paper which has been drawn up under our directions by the hydrographer, and you are to supply a copy thereof to the lieutenant commanding the Starling.
You are to leave no opportunity of transmitting to ​the hydrographer detailed accounts of the progress of the survey, as well as tracings of any part of the coast which may be completed. On every occasion which may offer, you are to address a brief report of your proceedings to our Secretary for our information, and at the expiration of three years passed in the execution of the above survey, you are, after communicating with the senior officer, to call at Valparaiso, and by rounding Cape Horn, to repair to Spithead, reporting your arrival and proceedings.
You are to prepare a berth for the botanical collector for plants and seeds for his Majesty's garden at Kew, who is to be borne on the book of the Sulphur for victuals only, and who will mess with the warrant officers; you will furnish him with the means of landing on such parts of the coast of the shores you may visit, to make his collection, when it will not interfere with the survey.
Should anything fatal happen to you on this side of America, the officer next in command is hereby required and directed to return with the Sulphur and Starling to Spithead, calling at Rio Janeiro, if already passed that place.
If that unfortunate event should happen to you on the western side of America, and during the first year, the officer next in command is to continue until the end of that fair weather season, on the work which may have been commenced, and then to return as above.
But should it occur after the vessels have begun their operations in the northern hemisphere, it may be presumed that the officer next in command will have acquired a sufficient acquaintance with your views to proceed with the remainder of the survey on his own ​resources, and he is hereby required and directed to carry these orders into execution accordingly.
Given, &c., 21st Dec. 1835.
(Signed) C. Adams.
Geo. Elliot.
To F. N. Beechey, Esq.,
    Subsequently Commander E. Belcher,
       Captain of his Majesty's surveying vessel
          Sulphur at Spithead,
    By, &c.
       (Signed) C. Wood.
N.B. While the Sulphur and Starling are within the limits of the South American Station you are to consider yourself under the command of Rear- Admiral Sir G. E. Hammond, the commander-in-chief on that station.
By the Commissioners for executing the office of Lord High Admiral of the United Kingdom of Great Britain and Ireland, &c.
Whereas we think fit that you shall be employed in superintending the survey of the coasts of the Pacific, and having ordered a passage for you in the Echo steam-vessel, to the West Indies, you are hereby required and directed to repair to Chagres, and there learning from his Majesty's consul the best way of crossing the isthmus, you will proceed to Panama, in order to assume the command of his Majesty's surveying vessel "Sulphur," and to take his Majesty's surveying vessel "Starling" under your orders.
Before you quit Chagres, you will make such ​arrangements as will prevent any loss of time in firing the rockets for determining the meridian distance across the isthmus.
This object having been effected, or found to be impracticable without serious delay, you are hereby required and directed to proceed forthwith to carry into execution our orders formerly given to your predecessor Captain Beechey, as well as the instructions of our hydrographer, which were framed under our directions; copies of both of which papers are herewith inclosed for your information and guidance.
But as it appears that Captain Fitz-Roy has continued the survey of the western coast of South America, from the termination of Captain King's Survey at the peninsula of Tres Monies as far as the Gulf of Guayaquil, you are to consider as executed so much of our orders to Captain Beechey; excepting such further details in that interval of coast as you may be directed to obtain in the additional instructions addressed to you by our hydrographer, which are herewith transmitted.
Given under our hands, the 16th of November, 1836.
minto.
Chas. Adams.
To Commander Edward Belcher,
    Appointed to command
       His Majesty's surveying vessel Sulphur.
By command of their Lordships.
John Barrow.