ADMIRALTY INSTRUCTIONS
FOR THE BEAGLE VOYAGE
[From Vol. 2, of Captain Robert FitzRoy's Narrative
of the surveying voyage of HMS Adventure and
Beagle, London, 1839]
Instructions
By the Commissioners for executing the office of Lord High Admiral ofthe United Kingdom
of Great
Britain and Ireland, &c.
You are hereby required and directed to put to sea, in the vessel you command, so
soon as she
shall be in every respect ready, and to proceed in her, with all convenient expedition, successively
to Madeira or Teneriffe; the Cape de Verd Islands; Fernando Noronha; and the South American
station; to perform the operations, and execute the surveys, pointed out in the accompanying
memorandum, which has been drawn up under our direction by the Hydrographer of this office;
observing and following, in the prosecution of the said surveys, and in your other operations, the
directions and suggestions contained in the said memorandum.
You are to consider yourself under the command of Rear Admiral Sir Thomas Baker, Commander-
in-chief of his Majesty's ships on the South American station, whilst you are within the limits of that
station, in execution of the services above-mentioned; and in addition to the directions conveyed to
you in the memorandum, on the subject of your supplies of provisions, we have signified to the
Rear-Admiral our desire that, whenever the occasion offers, you should receive from him and the
officers of his squadron, any assistance, in stores and provisions, of which you may stand in need.
But during the whole time of your continuing on the above duties, you are (notwithstanding
the 16th
article of the 4th section of the 6th chapter, page 78, of the General Printed Instructions) to send
reports, by every opportunity, to our Secretary, of your proceedings, and of the progress you make.
Having completed the surveys, which you are directed to execute on the South American
station,
you are to proceed to perform the several further operations set forth in the Hydrographer's
memorandum, in the course therein pointed out; and having so done, you are to return, in the
vessel you command, to Spithead, and report your arrival to our Secretary, for our information and
further directions.
In the event of any unfortunate accident happening to yourself, the officer on whom
the command of
the Beagle may in consequence devolve, is hereby required and directed to complete, as far as in
him lies, that part of the survey on which the vessel may be then engaged, but not to proceed to a
new step in the voyage; as, for instance, if at that time carrying on the coast survey on the western
side of South America, he is not to cross the Pacific, but to return to England by Rio de Janeiro
and the Atlantic.
[Memorandum]
A considerable difference still exists in the longitude of Rio de Janeiro, as determined
by Captains
King, Beechey, and Foster, on the one hand, and Captain W. F. Owen, Baron Roussin, and the
Portuguese astronomers, on the other; and as all our meridian distances in South America are
measured from thence, it becomes a matter of importance to decide between these conflicting
authorities. Few vessels will have ever left this country with a better set of chronometers, both
public and private, than the Beagle; and if her voyage be made in short stages, in order to detect
the changes which take place in all chronometers during a continuous increase of temperature, it
will probably enable us to reduce that difference within limits too small to be of much import in our
future conclusions.
With this view, the run to Rio de Janeiro may be conveniently divided into four parts:
Ist. Touching at Madeira, the exact position of which has been admitted by all parties.
Having
obtained a four days' rate there, or, if the weather and the exposed anchorage will not permit, at
Teneriffe, the Beagle should, 2ndly, proceed with the least possible delay to Port Praya, in the
Cape de Verd Islands, not only to establish a fresh four days' rate; but that point being the pivot
on
which all Captain Owen's longitudes turn, no pains should be spared in verifying the position he has
assumed for it. From thence, 3rdly, she should make the best of her way across the Line to
Fernando Noronha. This island, indeed, lies somewhat to the westward of her track, and may retard
her progress a little; yet a series of chronometric observations there is essential to the object in
view, because it forms the third nearly equal division of the whole run, and because it was the point
of junction of Commander Foster's double line of longitudes. If two or three days' delay at either of
these two last stations will enable him to obtain satisfactory occultations, and moon culminating
observations, which are likely to be seen in this country, the increased certainty of the results will
well atone for that loss of time. The Commander will, of course, be careful to adopt, in all those
stations, the precise spot of the former observations, with which his are to be compared. The
Governor of Fernando Noronha was peculiarly obliging to Commander Foster, and gave up part of
his own house for the pendulum experiments. There will be no occasion now for trespassing so
heavily on his kindness; but the difference of longitude between that station and Commander
FitzRoy's must be well measured.
However desirable it may be that the Beagle should reach Rio de Janeiro as soon as
possible, yet
the great importance of knowing the true position of the Abrolhos Banks, and the certainty that
they extend much further out than the limits assigned to them by Baron Roussin, will warrant the
sacrifice of a few days, if other circumstances should enableher to beat down about the meridian of
36ø W from the latitude of I6ø S. The deep sea-line should be kept in motion; and if soundings be
obtained, the bank should be pursued both ways, out to the edge, and in to that part already
known.
Its actual extent to the eastward, and its connection with the shoals being thus ascertained,
its
further investigation may be left to more convenient opportunities.
At Rio de Janeiro, the time necessary for watering, &c. will, no doubt, be employed
by the
commander in every species of observation that can assist in deciding the longitude of Villegagnon
Island.
It is understood that a French Expedition is now engaged in the examination of the
coast between
St Catherine's and the Rio de la Plata; it would therefore be a waste of means to interfere with that
interval; and Commander FitzRoy should be directed to proceed to Monte Video, and to rate his
chronometers in the same situation occupied by Captain King.
To the southward of the Rio de la Plata, the real work of the survey will begin. Of
that great extent
of coast which reaches from Cape St Antonio to St George's bay, we only know that it is
inaccurately placed, and that it contains some large rivers, which rise at the other side of the
continent, and some good harbours, which are undoubtedly worth a minute examination. Much of
it, however, from the casual accounts of the Spaniards, seems to offer but little interest either to
navigation or commerce, and will scarcely require more than to have its direction laid down
correctly, and its prominent points fixed. It should nevertheless be borne in mind there, and in other
places, that the more hopeless and forbidding any long line of coast may be, the more precious
becomes the discovery of a port which affords safe anchorage and wholesome refreshments.
The portions of the coast which seem to require particular examination are
Ist. From Monte Hermoso to the Rio Colorado, including the large inlet of Bahia Blanco,
of which
there are three manuscripts in this office that differ in every thing but in name.
2ndly. The gulf of Todos los Santos, which is studded in the Spanish charts with innumerable
islands and shoals. It is said to have an excellent harbour on its southern side, which should be
verified; but a minute survey of such an Archipelago would be a useless consumption of time, and it
will therefore be found sufficient to give the outer line of the dangers, and to connect that line with
the regular soundings in the offing.
3rdly. The Rio Negro is stated to be a river of large capacity, with settlements 50
miles from its
mouth, and ought to be partially reconnoitred as far as it is navigable.
4thly. The gulf of San Matias should be examined, especially its two harbours, San
Antonio and
San Jos‚, and a narrow inlet on the eastem side of the peninsula,
which, if easy of access, appears
to be admirably situated: and
5thly. From the Bahia Nueva to Cape Blanco, including the Gulf of St George, the coast
is of
various degrees of interest, and will accordingly require to have more or less time bestowed on its
different parts. The position of Cape Blanco should be determined, as there appears to be an error
of some miles in its latitude, as well as much doubt about the places of two shoals which are
marked near it in the Spanish charts.
From Cape Blanco to the Strait of Magalhaens, the coast has been partially corrected
by Captain
King; and Port Desire, having been carefully placed by him, will afford a good place for rating the
chronometers, and an opportunity for exploring the river.
Port San Julian, with its bar and wide river, should be surveyed, as well as any parts
of that interval
which were not visited in the last expedition.
The above are the principal points of research between the Rio de la Plata and the
Strait. They have
been consecutively mentioned in order to bring them into one point of view; but that part of this
service would perhaps be advantageously postponed till after the Beagle's first return from the
southward; and, generally speaking, it would be unwise to lay down here a specific route from
which no deviation would be permitted. Where so many unforeseen circumstances may disturb the
best- concerted arrangements, and where so much depends on climates and seasons with which
we are not yet intimately acquainted, the most that can be safely done is to state the various
objects of the voyage, and to rely on the Commander's known zeal and prudence to effect them in
the most convenient order.
Applying this principle to what is yet to be done in the Strait, and in the intricate
group of islands
which forms the Tierra del Fuego, the following list will show our chief desiderata.
Captain King, in his directions, alludes to a reef of half a mile in length, off Cape
Virgins, and in his
chart he makes a 7 fathoms' channel outside that reef; and still further out, 5 fathoms with overfalls.
Sarmiento places 50 fathoms at IO miles ESE from that Cape; I3 fathoms at I9 miles; and, at 2I
miles in the same direction, only 4 fathoms, besides a very extensive bank projecting from Tierra
del Fuego, between which and the above shoals Malaspina passed in I3 fathoms. In short, there is
conclusive evidence of there being more banks than one that obstruct the entrance to the Strait,
and undoubtedly their thorough examination ought to be one of the most important objects of the
Expedition; inasmuch, as a safe approach to either straits or harbours is of more consequence to
determine than the details inside.
None of the above authors describe the nature of these shoals, whether rock or sand;
it will be
interesting to note with accuracy the slope, or regularity, of the depths, in their different faces,
the
quality of their various materials, and the disposition of the coarse or fine parts, as well as of what
species of rock in the neighbourhood they seem to be the detritus; for it is probable that the place
of their deposition is connected with the very singular tides which seem to circulate in the eastern
end of the Strait.
Beginning at Cape Orange, the whole north-eastern coast of Tierra del Fuego as far
as Cape San
Diego should be surveyed, including the outer edge of the extensive shoals that project from its
northern extreme, and setting at rest the question of the Sebastian Channel.
On the southern side of this great collection of islands, the Beagle Channel and Whale-boat
Sound
should be finished, and any other places which the Commander's local knowledge may point out as
being requisite to complete his former survey, and sufficiently interesting in themselves to warrant
the time they will cost; such as some apparently useful ports to the westward of Cape False, and
the north side of Wakefield Channel, all of which are said to be frequented by the sealers.
In the north-westem part it is possible that other breaks may be found interrupting
the continuity of
Sta Ines Island, and communicating from the Southern Ocean with the Strait; these should be fully
or cursorily examined, according to their appearance and promise; and though it would be a very
useless waste of time to pursue in detail the infinite number of bays, openings, and roads, that
teem on the western side of that island, yet no good harbour should be omitted. It cannot be
repeated too often that the more inhospitable the region, the more valuable is a known port of
refuge.
In the western division of the Strait, from Cape Pillar to Cape Froward, there are
a few openings
which may perhaps be further explored, on the chance of their leading out to sea; a few positions
which may require to be reviewed; and a few ports which were only slightly looked into during
Captain King's laborious and excellent survey, and which may now be completed, if likely to
augment the resources of ships occupied in those dreary regions.
In the eastern division of the Strait there is rather more work to be done, as the
Fuegian shore from
Admiralty Sound to Cape Orange has not been touched. Along with this part of the service, the
Islands of Saints Martha and Magdalena, and the channel to the eastward of Elizabeth Island, will
come in for examination and there is no part of the Strait which requires to be more accurately laid
down and distinctly described, from the narrowness of the channels and the transverse direction of
the tides. Sweepstakes Foreland may prove to be an Island; if so, there may be found an useful
outlet to the long lee- shore that extends from Cape Monmouth; and if not, perhaps some safe
ports might be discovered in that interval for vessels caught there in strong westerly gales.
It is not likely that, for the purposes of either war or commerce, a much more detailed
account will
be necessary of those two singular inland seas, Otway and Skyring Waters, unless they should be
found to communicate with one of the sounds on the western coast, or with the western part of the
Strait. The general opinion in the former Expedition was certainly against such a communication,
and the phenomena of the tides is also against it; still the thing is possible, and it becomes an
interesting geographical question, which a detached boat in fine weather will readily solve.
These several operations may probably be completed in the summer of I833-34, including
two trips
to Monte Video for refreshments; but before we finally quit the eastern coast of South America, it is
necessary to advert to our present ignorance of the Falkland Islands, however often they have been
visited. The time that would be occupied by a rigorous survey of this group of islands would be very
disproportionate to its value; but as they are the frequent resort of whalers, and as it is of immense
consequence to a vessel that has lost her masts, anchors, or a large part of her crew, to have a
precise knowledge of the port to which she is obliged to fly, it would well deserve some sacrifice of
time to have the most advantageous harbours and their approaches well laid down, and connected
by a general sketch or running survey. Clear directions for recognizing and entering these ports
should accompany these plans; and as most contradictory statements have been made of the
refreshments to be obtained at the east and west great islands, an authentic report on that subject
by the Commander will be of real utility.
There is reason to believe that deep soundings may be traced from these islands to
the main, and
if regular they would be of great service in rectifying a ship's place.
Having now stated all that is most urgent to be done on this side of the South American
Continent
as well as in the circuit of Tierra del Fuego, the next step of the voyage will be Concepcion, or
Valparaiso, to one of which places the Beagle will have to proceed for provisions, and where
Captain King satisfactorily determined the meridian distances.
The interval of coast between Valparaiso and the western entrance of the Strait has
been partly
surveyed, as well as most of the deep and narrow channels formed by the islands of Hanover,
Wellington, and Madre de Dios; but of the sea face of that great chain of islands which stretches
from Queen Adelaide Archipelago to Campana Island, little has yet been done. It presents a most
uninviting appearance, can probably afford but little benefit to the navigator, and the chief object
in
urging its partial examination, is to remove a blank from this great survey, which was undertaken by
Great Britain from such disinterested motives, and which was executed by Captains King and
FitzRoy with so much skill and zeal.
The experience gained by the latter in that climate will enable him to accomplish
all that is now
required in much less time than it would have occupied in the beginning of the former expedition.
At the Gulf of Penas the last survey terminated. Of the peninsula de Tres Montes,
and of the
islands between that and Chiloe, a Spanish manuscript has been procured &om Don Felipe Bauza,
which may greatly abridge the examination of that interval.
From thence to Valdivia, Concepcion, and Valparaiso, the shore is straight, and nearly
in the
direction of the meridian, so that it will require no great expenditure of time to correct the outline,
and to fix the positions of all the salient points. Mocha Island is supposed to be erroneously
placed: and the depth, breadth, and safety of its channel are not known.
To the south of Valparaiso the port of Topocalmo and the large shoal in the offing
on which an
American ship was wrecked, require special examination, and according to Captain Burgess, of the
Alert, the coast and islands near Coquimbo are very imperfectly laid down. Indeed of the whole of
this coast, the only general knowledge we have is from the Spanish charts, which seem, with the
exception of certain ports, to have been merely the result of a running view of the shore. Of this
kind of halfknowledge we have had too much: the present state of science, which affords such
ample means, seems to demand that whatever is now done should be finally done; and that
coasts, which are constantly visited by English vessels, should no longer have the motley
appearance of alternate error and accuracy. If, therefore, the local Governments make no
objections, the survey should be continued to Coquimbo, and indefinitely to the northward, till that
period arrives when the Commander must determine on quitting the shores of South America
altogether. That period will depend on the time that has been already consumed, and on the
previous management of his resources, reserving sufficient to ensure his obtaining a series of well-
selected meridian distances in traversing the Pacific Ocean.
The track he should pursue in executing this important duty cannot well be prescribed
here, without
foreseeing to what part of the coast he may have pushed the survey, and at what place he may find
it conv‚nient to take in his last supplies. If he should reach
Guayaquil, or even Callao, it would be
desirable he should run for the Galapagos, and, if the season permits, survey that knot of islands.
Felix Island, the London bank seen by the brig Cannon, in I827, in 27ø 6~ S 92ø I6t W, even
with
the water's edge, and half a mile in length; some coral islands, supposed to be 5ø or 6ø south
of
Pitcairn Island, and other spots, which have crept into the charts on doubtful authority, would all
be
useful objects of research if the Beagle's route should fall in their vicinity. But whatever route may
be adopted, it should conduct her to Tahiti, in order to verify the chronometers at Point Venus, a
point which may be considered as indisputably fixed by Captain Cook's and by many conarrent
observations. Except in this case, she ought to avoid as much as possible the ground examined by
Captain Beechey.
From Tahiti the Beagle should proceed to PortJackson touching at some of the intervening
islands,
in order to divide the run into judicious chronometer stages; for the observatory at Paramatta
(PortJackson) being absolutely determined in longitude, all those intervening islands will become
standard points to which future casual voyagers will be able to refer their discoveries or correct their
chronometers.
From Port Jackson her course will depend on the time of the year. If it be made by
the southward,
she might touch at Hobart Town, King George Sound, and Swan River, to determine the difference
of longitude from thence to the Mauritius, avoiding the hurricane months; to Table or Simon's Bay,
according to the season; to St. Helena, Ascension, and home.
If she should have to quit PortJackson about the middle of the year, her passage must
be made
through Torres Strait. In her way thither, if the in- shore route be adopted, there are several places
whose positions it will be advantageous to determine: Moreton Bay, Port Bowen, Cape Flinders,
and one of the Prince of Wales Islands; and in pursuing her way towards the Indian Ocean, unless
the wind should hang to the southward, Cape Valsche or the south- west extreme of New Guinea,
one of the Serwatty Chain, Coupang, or the extreme of Timor, Rotte Island, and one of the
extremes of Sandalwood Island, may be easily determined without much loss of time. And,
perhaps, in crossing the ocean, if circumstances are favourable, she might look at the Keeling
Islands, and settle their position.
Having now enumerated the principle places at which the Beagle should be directed
to touch in her
circuit of the globe, and described the leading operations which it would be desirable to effect, it
remains to make some general remarks on the conduct of the whole survey.
In such multiplied employments as must fall to the share of each officer, there will
be no time to
waste on elaborate drawings. Plain, distinct roughs, every where accompanied by explanatory
notes, and on a sufficiently large scale to show the minutiae of whatever knowledge has been
acquired, will be documents of far greater value in this office, to be reduced or referred to, than
highly finished plans, where accuracy is often sacrificed to beauty.
This applies particularly to the hills, which in general cost so much labour, and
are so often put in
from fancy or from memory after the lapse of months, if not of years, instead of being projected
while fresh in the mind, or while any inconsistencies or errors may be rectified on the spot. A few
strokes of a pen will denote the extent and direction of the several slopes much more distinctly
than the brush, and if not worked up to make a picture, will really cost as little or less time. The
in-
shore sides of the hills, which cannot be seen from any of the stations, must always be mere
guess-work, and should not be shown at all.
It should be considered an essential branch of a nautical survey, to give the perpendicular
height of
all remarkable hills and headlands. It requires but a single angle at each station, adds much to our
geographical knowledge, materially assists the draftsman, and by tables which are now printing it
will afford to the seaman a ready and exact means of knowing his distance.
All charts and plans should be accompanied by views of the land; those which are to
be attached
to the former should be taken at such a distance as will enable a stranger to recognize the land, or
to steer for a certain point; and those best suited for the plan of a port should show the marks for
avoiding dangers, for taking a leading course, or choosing an advantageous berth. In all cases the
angular distances and the angular altitudes of the principal objects should be inserted in degrees
and minutes on each of the views, by which means they can be projected by scalej so as to
correct any want of precision in the eye of the draftsman. Such views cannot be too numerous;
they cost but a few moments, and are extremely satisfactory to all navigators.
Trifling as it may appear, the love of giving a multiplicity of new and unmeaning
names tends to
confuse our geographical knowledge. The name stamped upon a place by the first discoverer
should be held sacred by the common consent of all nations; and in new discoveries it would be far
more beneficial to make the name convey some idea of the nature of the place; or if it be inhabited,
to adopt the native appellation, than to exhaust the catalogue of public characters or private friends
at home. The officers and crews, indeed, have some claim on such distinction, which, slight as it
is, helps to excite an interest in the voyage.
Constant observations on the tides, including their set, force, and duration, the
distance to which
they carry salt water up the rivers, their rise at the different periods of the lunation, and the extent
to which they are influenced by the periodic winds, by the sea currents, or by the river freshes, form
so prominent a part of every surveyor's duty, that no specific directions on this subject can be
necessary. Nor is there any occasion to insist here on the equally important subject of currents; for
it is only by a great accumulation of data that we can ever hope to reduce them to regular systems,
or that we can detect the mode in which they are affected by change of seasons, or influenced by
distant winds.
The periods and limits of the monsoons and trade winds will naturally be a continual
object of the
Commander's observation and study. It is true that he can only witness what occurs during his
voyage; but besides collecting facts on this and the last subject, on which others can hereafter
reason, it will be of immense advantage that he should endeavour to digest them with the remarks
of former voyagers when on the spot.
On the western coast of South America, for instance, some skill is required in making
passages at
different periods, and much scattered experience has been gained by seamen who have been long
occupied there; but this information has not yet been presented to the public in an intelligible form;
and it seems to be the peculiar province of an officer expressly employed on a scientific mission
like this, to combine that information with his own, and to render it accessible to every navigator.
The local attraction of the Beagle will of course have been ascertained before she
leaves England;
but when favourable opportunities occur, it will be satisfactory to swing her again in different
latitudes, and under large differences of variation.
No day should pass at sea without a series of azimuths, and no port should be quitted
without
having ascertained not only the magnetic angle, but the dip, intensity, and diurnal variation. If these
observations should have been well made in the same places before, we shall at once obtain the
annual change; and by multiplying them in new places, we shall have the means of inferring the
magnetic curves.
The Commander has been so accustomed to the management of chronometers, that there
is no
doubt, with proper precautions and with proper formul‘ for determining
their rates, that he will
succeedsin obtaining good results in reasonably short intervals of time and in gradual changes of
temperature; but after long periods, and sudden changes of heat and cold, it will be absolutely
necessary to check them by astronomical means.
Eclipses, occultations, lunar distances, and moon- culminating stars, will furnish
those means in
abundance: of all these, the last can be obtained with the greatest regularity and certainty; they
have become part of the current business at the establishments of the Cape of Good Hope,
Paramatta, and St Helena, in the southern hemisphere; probably at Madras, and in many of the
European observatories and it will therefore be scarcely possible that there should not be
corresponding observations for all such as he may have made.
The eclipses of Jupiter's third and fourth satellites should also be sedulously observed
whenever
both immersion and emersion can be seen, as the different powers ofthe telescopes employed by
the observers do not in that case affect the results.
There are also some remarkable phenomena, which will be announced in the Nautical
Almanacks,
and which will occur during the Beagle's voyage. Some of these will be highly interesting to
astronomers, and if it would not much derange her operations, she should be taken to some
convenient anchorage for the purpose of landing the instruments.
If a comet should be discovered while the Beagle is in port, its position should be
determined every
night by observing its transit over the meridian, always accompanied by the transits of the nearest
known stars, and by circum-meridional altitudes, or by measuring its angular distance from three
well- situated stars by a sextant. This latter process can be effected even at sea, and the mean of
several observations may give very near approximations to its real position.
Meterological Registers may be of use in a variety of ways; but then they must be
steadily and
accurately kept. The barometer should be read off to the third place of decimals, and recorded at
regular periods of the day; nine o'clock and four o'clock may be recommended as the best, as
being the usual hours of its maximum and minimum. The temperature should be marked at the
same time, and the extremes of the self-registering thermometer should be daily recorded; care
being taken that no reflected heat should act on any ofthese instruments. The temperature ofthe
sea at the surface ought to be frequently observed and compared with that of the air. An officer
cruising on the east coast of South America, between the parallels of 20ø and 35ø, was enabled by
these means to predict with singular precision the direction and strength of the current.
In this register the state of the wind and weather will, of course, be inserted; but
some intelligible
scale should be assumed, to indicate the force of the former, instead of the ambiguous terms
'fresh', 'moderate', &c., in using which no two people agree; and some concise method should also
be employed for expressing the state of the weather. The suggestions contained in the annexed
printed paper are recommended for the above purposes, and if adopted, a copy should be pasted
on the first page of every volume of the log-book; and the officer of the watch should be directed to
use the same terms in the columns of the log-board.
The circularly formed Coral Islands in the Pacific occasionally afford excellent land-locked
harbours, with a sufficient entrance, and would be well adapted to any nice astronomical
observations which might require to be carried on in undisturbed tranquillity. While these are quietly
proceeding, and the chronometers rating, a very interesting inquiry might be instituted respecting
the formation of these coral ree&. +
An exact geological map of the whole island should be constructed, showing its form,
the greatest
height to which the solid coral has risen, as well as that to which the fragments appear to have
been forced. The slope of its sides should be carefully measured in different places, and particularly
on the external face, by a series of soundings, at very short distances from each other, and carried
out to the greatest possible depths, at times when no tide or current can affect the perpendicularity
of the line. A modem and very plausible theory has been put forward, that these wonderful
formations, instead of ascending from the bottom of the sea, have been raised from the summits of
extinct volcanoes; and therefore the nature of the bottom at each of these soundings should be
noted, and every means exerted that ingenuity can devise of discovering at what depth the coral
formation begins, and of what materials the substratum on which it rests is composed. The shape,
slope, and elevation of the coral knolls in the lagoon would also help the investigation; and no
circumstances should be neglected which can render an account of the general structure clear and
perspicuous.
A set of observations connected with the theory of the tides might likewise be carried
on with
peculiat propriety in one of these coral basins, provided the openings should be sufficiently wide
and deep to admit the flux and reflux without material impediment. The island selected for such a
purpose should be nearly midway in the ocean, and not very far from the equator.
There the tidal wave, uninfluenced by the interrupting barrier of one continent, and
equally fa} from
the reaction of the other, might be measured with very beneficial results. Delicate tidegauges
should be prepared beforehand, and immediately fixed in some snug nook, where the undulation
ofthe sea could not reach. The rise and fall of the tide should be registered every hour, during the
stay of the Beagle, as well as the moments (stated whether in apparent or mean time) of high and
low water, as nearly as they can be obtained; and the periods at which the sea and land breezes
spring up and fail should likewise be noted, with their effects on the tide, if they can be detected.
A
boat should be detached, on each tide, to some distance from the island, in order to ascertain the
strength and direction of the stream; and all these operations should be continued, if possible,
through a whole lunation.
Compiling general and particular instructions, for the navigation of all the places
which he may visit,
will of course be an essential part of the Commander's duty; but he will also have innumerable
opportunities of collecting a variety of auxiliary information, which, when judiciously combined with
the above instructions, of a purely nautical character, will much enhance their utility to all dasses
of
vessels. Such as the general resources on which ships may depend in different places: the chief
productions that can be obtained, and the objects most anxiously desired in retum: the effect of
seasons, of climate, and of peculiar articles of food on the health of the crew, and many others
which will readily occur to his mind, and which become of great value to a stranger.
On all the subjects touched on in these memoranda, Commander FitzRoy should be directed
to
draw up specific reports, and to transmit them from time to time, through their Lordship's
Secretary, to the Hydrographic Office, so that if any disaster should happen to the Beagle, the
fruits of the expedition may not be altogether lost. Besides such reports, and with the same object
in view, he should keep up a detailed correspondence by every opportunity with the Hydrographer.
The narrative of every voyage in the Pacific Ocean abounds with proofs of the necessity
of being
unremittingly on guard against the petty treacheries or more daring attacks of the natives. It should
be recollected that they are no longer the timid and unarmed creatures of former times, but that
many of then now possess fire-arms and ammunition, and are skilful in the use of them. Temper
and vigilance will be the best preservatives against trivial offences and misunderstandings, which
too often end in fatal quarrels; and true firmness will abandon objects of small importance, where
perseverance must entail the necessity of violence; for it would be a subject of deep regret that an
expedition devoted to the noblest purpose, the acquisition of knowledge should be stained by a
single act of hostility.