1847 Letter – transcribed by William Maury Morris 2nd.
To President John Quincy Adams.
From Lieutenant Matthew Fontaine Maury, U. S. Navy
Addressed to the Hon. John Quincy Adams.
Dear Sir,—You did me the honor yesterday to ask that I would give a written description of the Observatory, with other information relating thereto, including an explanation of the object and uses of the different instruments.
I need not speak of the pleasure it gives me to comply with your request; the only alloy to this pleasure is found in the circumstance that I have not the leisure, and if the leisure, not the ability to make the answer as full or satisfactory as I would have it.
Your efforts to advance America in the cause of practical Astronomy, are known to the world. The lively interest which you continue to manifest in all that concerns the Observatory, causes you to be considered as one of its most active and zealous friends. It is proud of the relation. It feels honored, and is encouraged by every additional proof of the interest felt by you in its pursuits and for its prosperity.
As a subject for congratulation with one who has born so conspicuous a part in establishing a Naval and National Observatory in this country, permit me to call your attention to the interest, which, since the establishment of the government of such an Institution, as commenced to manifest itself in the public mind in the cause of practical Astronomy.
The Act of Congress in founding this establishment, was passed in 1842. Since that time public meetings have been held, plans matured, and subscriptions proposed in various parts of the country for establishing Observatories. It is not hazarding too much to say that within the last five or six years, more has been done in the United States to encourage and advance Astronomical science, and that more has been added to the general stock of such knowledge, than during the whole period of our previous existence, either as a nation or a people; and in this fact, the friends of the science do but recognize the first fruits of the seeds that were cast by you many years ago.
There never has been, in the history, of Astronomy, a period of so much activity and energy as that of the present. Within the last two years, the names of four new members have been added to the list of planets.
(  Since this was written another planet has been discovered. Flora is its name, and it is 8th in the family of Asteroids.)
Within this time the world has been astonished, and the mightiest intellects in it have considered admiration with the feats that have been performed by men that are engaged in Astronomical pursuits. The most remote planet known to the system was subject to perturbations from an unknown cause. The disturbance was far beyond the unaided eye; and was unknown to telescopic vision. But there were Astronomers living who, for the first time, undertook to invest mathematical analysis with the space-penetrating power of the telescope. They succeeded in the bold attempt and from the closest pointed the observer’s telescope to the locus of the stranger. The circumstances connected with the discovery of the planet Neptune are alone sufficient to stamp the age in which we live, as a remarkable era in the progress of Astronomy. So too with regard to Struve’s “Stellar Astronomy” and Madler’s “Central Sun.” This object or point, invisible though it be, and incorporeal though it may be, has been made to “tremble on the verge of analysis.” These illustrious savants, with a degree of probability and a force of reasoning, that every where have arrested the attention of Astronomers and challenged the respect of Mathematicians, have shown that the sun, moon, and planets with their train of satellites and comets, are in motion as a unit, if I may be allowed the figure, about some grand centre poised in the remote regions of space; and situated in the direction of the Pleiades towards the star Alcyone. Perhaps this point is also the “Central Sun” about which the suns of a thousand other systems hold their way. Our luminary with its splendid retinue, is computed to revolve about this centre at a rate of not less than thirty millions of miles in a year; yet so remote is it that many millions of our years are required for the completion of one revolution. Here then, indeed, is an “annus magnus” of vast import In the contemplation of it, may we not regard those comets which dash through our system, never to return, as lights sent from other systems to guide us on our way? Or at least may we not feel assured that they answer wise and useful purposes in the great economy?
I might point to other triumphs of mind over matter, in illustration of length of line which Astronomers and Mathematicians are casting out, to fathom and explore the regions of space.
Pingre’s comet is just now about to make its appearance for the third recorded time, to the inhabitants of the earth. On the occasion of each of its former visits, it carried terror and dismay to the minds of Kings and Princes. In 1264 it was regarded, as a messenger charged with the execution of sentence of death of Pope Urban IV.
At its next return Emperor Charles V. of Spain wrote of it, “His ergo indiceis me mea fala vacant.” It is said that he resigned his crown to prepare for the dread summons.
It has now been gone for another period of nearly three hundred years, and is soon to come back provided with an “arming” which will be as significant to the Astronomer of what it has encountered in the depths of space, as is of the depths of the ocean, the sand to the mariner which adheres to his lead.
But so far from its expected appearance in 1848, being cause of dread and alarm to Powers and Potentates, its coming is looked for even by the multitude, with a degree of eager interest and will be hailed with pleasure and delight in many lands.
From a mysterious messenger bringing tidings of a dreadful, potent and awful calamity to a terror stricken world, Astronomy by its progress has changed in the minds of men the character of comets; they have been made obedient to law, subservient, instructive and useful to man, in his upward and onward progress. They teach important truths and assist, to reveal the secrets of nature.
You yourself, may recollect the time when Astronomers were called upon to quiet the public mind in one of the most refinedé capitals of Europe, and soothe the dreadful apprehensions with which the approach of a comet was regarded Yet even during a short interval, such has been the activity and the progress in this department of science, that comets have ceased to be regarded as objects of terror sent, at long intervals, to warn or to punish; they are rather looked upon as fellow-travellers and instructive companions to man in his journeys through space.
Instead of years, scarcely a month now elapses without the announcement that some new comet has been discovered; such is the activity of research. The people of America have caught up the spirit, and are beginning actively to engage in Astronomical pursuits.
 The last Comet discovered (Oct. 1st, 1847) was made by a lady of your own State—(#1 Miss Mitchell of Nantucket.) She has also computed its orbit. Thus #2 .Maria Mitchell’s Comet is another evidence of the attention which the subject of Astronomy is exciting in this country.
You have had the subject, as far as this country is concerned, anxiously at heart for years: wherefore I consider the present occasion as one for congratulation. Pardon, therefore, for the digression.
The Astronomical instruments of the Observatory, with Telescopes attached, are six. The regular Observers, eight.
1st. The West Transit Instrument, made by Ertel & Son, of Munich. Observers, Mark H. Beecher and Ruel Keith, Professors of Mathematics, U. S. N.
2nd. The Mural Circle, made by Tungton & Simms, London. Observers, Thomas J. Page & Charles Steedman, Lieutenants and J. H. C. Coffin, Professor of Mathematics, U. S. N.
3rd. The Meridian Circle, Ertel & Son. Observers, William T. Muse, Lieutenant, and James Major, Professor of Mathematics, U. S. N.
4th. The Prime Vertical Transit Instrument, Pistor & Martins, Berlin. Observers, W. A. Wayne, U. S. N. and James Johnson Pittigrew, a young Mathematician from North Carolina.
5th. The Equatorial, Murz & Mahler, Munich. Occasional Observers, myself and Joseph S. Hubbard, Professor of Mathematics, U. S. N.
6th. The “Great Refraction Circle,” Ertel & Son, Munich. Observers, none.
Lieutenant Page is in daily expectation of orders to sea, and Lieutenant Steedman has been in training to take his place at the Mural. Hence the names of three officers for that Instrument. Professor Hubbard has been recently detailed for duty not connected with the Observatory. When he returns he will observe regularly with the Equatorial.
As soon as practicable, I propose to place also Professor Keith at the Refraction Circle.
It is a rule among Astronomers to consider an additional assistant at an Observatory which has as many as two Observers already employed, to be worth more than two better men at a new Observatory.
Considering that the expense of buildings, piers, and instruments has already been incurred for this Observatory—it is obviously more in conformity with the principles of true economy. To apply force enough to give the instruments full occupation whenever the weather will admit, than to only have them half-manned, or feebly served.
Accordingly, I have consistently aimed to have at least two observers at each instrument; so when the night is clear there will be always an eye for every Telescope in the Observatory.
But the unusual demand for officers afloat on the one hand and their anxiety for war service on the other, have made it difficult, during the last year, to keep at the Observatory its full compliment of observers.
The West Transit Instrument is mounted on the Meridian in the West wing of the Observatory. It has an object glass of 5.4 inches aperture, with a focal length of 7 feet 1 inch. A clock is an indispensable companion of this instrument, as a time-keeper of some sort is of every Astronomical Telescope. The clock is a mercurial pendulum, by Parkinson and Frodsham.
The Transit instrument affords data for the determination of Right Ascensions. By it time is determined—clocks rated, etc.
The Mural Circle, with the Meridian Circle, is mounted in the East wing. It is five feet in diameter and has a Telescope with an object glass of 4.1 inches aperature, and five feet focus. The Mural Circle is for the determination of Declinations. By it Latitude is also determined.
The Meridian Circle has a Microscope Bearer with 4 Microscopes; and two circles of 30 inches, diameter, one for degrees and minutes, and the other for seconds, connected with a telescope of 3.8 inches aperture, and four feet 11 inches focal length. Clock, mercurial pendulum, Charles Frodsham. This clock also answers for the Mural.
This instrument unites the transit instrument and the Mural Circle. It is for the determination for both co-ordinates.
The Prime Vertical Transit Instrument is mounted on the Prime Vertical in the first apartment of the South wing. It has no circle except a finder. The telescope has a focal length of 6 ½ feet and 4.8 inches aperature. Clock, grid-iron pendulum, Charles Frodsham.
This instrument is also for the determination of Right Ascensions and Declinations. But while it is capable of a higher degree of accuracy than anyone of the aforementioned, it is confined to a more narrow field; it works more slowly and cannot compete with its compeers in number or subjects of observation. They can observe all objects that appear above the horizon and cross the meridian—those only which cross its prime vertical—which in this instance embraces those stars which parallels of Declination are included between the Equator and the Zenith of this Observatory.
The Declinations determined with this instrument are surprisingly accurate. It is capable of affording results possessed of a higher degree of accuracy perhaps from those obtained from any other instrument known to Astronomy. This is in part owing to physical and mathematical advantages derived from its position in the prime vertical and partly to mechanical and instrumental peculiarities. It is a new instrument; it was invented by the direction of the Central Observatory of Russia, and this is the only other instrument of the kind except his.
Its position frees its results from and makes them independent of the effects and uncertainties of atmospherical refraction, and of the numerous imperfections and sources of error to which instruments with graduated arcs and circles are liable. Its peculiar construction and extraordinary facilities of reversal, neutralize other instrumental imperfections which are, other fruitful sources of error whenever their effects remain for the skill and patience of the observer to detect and expose. It is particularly well adapted for investigating the problem of the Stellar Parallax.
The equatorial has an object glass of 9.6 inches of aperature and 14 ½ feet focal length. It is provided with clock work for siderial motion, and the observations are timed from a siderial chronometer rated by the clocks below. It rests in the dome and surmounts a massive block of granite which is supported by a conical pier of brick work, rising from the foundation of the building and passing up in isolation of the floors and all other parts of the observatory.
Each one of the other instruments moves in the plane of but one great circle, and is capable of observing only as the object to be observed crosses such great circle, which, with the first three named, is the Meridian and with the fourth and sixth is the Prime Vertical.
The object of the Equatorial is to observe occultations and eclipses to determine the places of comets and planets by differential measurements. It is also used for measuring the angular distance and position between double stars, for measuring the diameter of planets, etc. It may be turned for observations at any time upon any object at whatever part of the visible heavens. Its greater optical and space-penetrating powers invest its labors in physical Astronomy with exceeding interest and give it other advantages, which are not possessed by its more humble companions below, though for differential position it is subsidiary to and dependent upon their determinations.
The Refraction Circle has two Microscope Bearers, which carry six microscopes each; two graduated circles of 4 feet each, with divisions for every 2 feet of arc on gold and a Telescope of 5.8 inches clear aperature and 8 ½ feet focal length. This instrument is new in its combinations and construction. It unites the exquisite accuracy of the Prime Vertical Transit instrument, with all of the advantages, compass, and capabilities of the Mural Circle and Zenith Sector. It is the first of its kind ever made, and was constructed from plans and drawings prepared at this Observatory. The makers pronounce it to be the most complete astronomical instrument that has ever left their hands. Its performance, however, remains to be tried.
Equally adapted for mounting on the Meridan or the Prime Vertical, it surpasses all of the first four instruments mentioned for power and compass: and in means for imparting accuracy to results, it possesses advantages which none of them have.
It is situated in the second apartment of the South wing, which has been extended to receive it. It is, at present, mounted on the Prime Vertical, but its ultimate destination is the Meridian.
It is the only Astronomical instrument which has ever been constructed and mounted, that independent of any previous hypothesis is capable of determining directly and immediately the effect of atmospherical refractions in optically displacing heavenly bodies. It is the first instrument ever used on this continent for the investigation of this most important problem; it will begin these investigations on the Prime Vertical and end them on the Meridan. Hence it is called the Refraction Circle, though there are many other subjects and problems towards the affording of data for the solution or investigation of which it is equally well adapted.
Theory points to perturbations by the moon and planets upon the earth’s centre of gravity. These daily disturbances, except as their effects are exhibited by the tides of the ocean or marked by the p.7 Barometer, have never, that I am aware of, been the subject of direct observation
This instrument, therefore, suggests a class of observations entirely new. And it is proposed to undertake them: for, whether sucessful, or not, the experiment will not be needless; but in either event will be possessed of both interest and value.
In consequence of the influence of the moon and other bodies, the centre of attraction of the earth may be supposed to revolve about its geometrical centre. It may be that this instrument is capable of determining, by actual observation, the orbit which one of these centres makes about the other; for, by an optical artifice, the centre of attraction, so to speak, or, which is the same thing (the nadir point, which is in a line with this centre) may be rendered visible; it only remains to be seen whether this instrument has power sufficient to detect its minute changes. Permit me to explain —
By turning the Telescope down upon a basin of mercury, the image of the spider-thread which is placed in the stellar focus of the object glass of the Telescope, may be seen as though it were an object at an infinite distance. Resorting to this optical artifice, by which the most attenuated line is placed in the nadir and directly in line with the centre of gravitation and taking advantage of the peculiar and extraordinary collimating powers of this instrument, it will be impossible for any deviation of the plumment amounting on the surface of the earth to as much as the breadth of the finest gossamer, from its normal state to escape observation. Permit me to illustrate by example:
Suppose the moon to be on the meridian at its lower culmination, and that the spider line in the focus of the Telescope be made to occult its own image over a basin of mercury and as seen in the nadar, we shall then have the most perfect plummet that can be dropped. The position of the Telescope is then noted, and in this position it remains. Suppose now after the moon rises, and reaches that altitude in the East at which her disturbance of the plummet is a maximum, that the Telescope is then again examined and the spider-thread and its image found to be no longer in occultation. This assuming stability in all other respects to be perfect, will be owing to the fact, that the centre of attraction has changed its position, and passed, also, to the East of the geometrical centre, so to speak, of the earth, and, in consequence, the mercury in the basin has adapted itself to this new centre, and, therefore, changed its inclination, by an amount equal to the defelection that would be produced upon the plummet. The maximum effect of this change, being seen by reflection, is apparently doubled.
When the moon reaches a like altitude in the West, the same takes place. But, in this instance, the image appears to the West, instead of the East of the real thread and the effect is again doubled, but on the side opposite the first. Thus the maximum deviation will multiplied four times, and so multiplied, will be brought under the highest magnifying powers of the instrument for detection and observation.
The facility with which the instrument is reversed and the manner in which it is supported on its pier, will impart to its results a degree of confidence as to the accuracy of determination that but few instruments have ever afforded.
But it would be altogether out of place and premature to discuss its powers here, or to anticipate results. I, therefore, pass on to the other subjects upon which you desire information.
According to the British Association, for the advancement of science, the vast sums of money which have been spent by Astronomers in doing over again what has been done better elsewhere, in determining Astronomical data, might have almost created new sciences of observation.
Not to make this Observatory liable to such a charge, a plan has been adopted for its labors which, while the plan seeks to avoid what has already been well done, aims at results both useful to the world and creditable to the country. The general outlines of this plan are to keep up a regular and systematic series of observations upon the sun, moon, and planets and certain fundemental stars, with the view of procuring data for the American Nautical Almanac. But the Observers and instruments are capable of many more observations than these; and with the views of fully occupying the time of each; at an early day, proposed regularly and systematically to penetrate, with our excellent Telescope, every point of space in the visible heavens, with the view of assassigning position and magnitude, and of cataloging every star, cluster, nebulae, or object that should pass through the field of view.
Leave what was sought and regularily granted, to carry this plan into effect, and the labor of near two years has already been expended upon it. A catalogue ofabout 1,200 stars, most of them unknown in existing catalogues, is the result of the first year’s work in this field.
The plan originally contemplated and designed is to sweep over the same belt twice, but not on the same night, nor with the same instrument or observer. Supposing the conditions of atmosphere, instrument, and eye to be the same, all the stars, and no more, which are observed during the first sweep, should be observed during the second. The work in this case is complete.
But suppose, and this is generally the case, that stars are observed in one sweep which are not observed in the other, the Equatorial is turned upon the same belt to reconcile discrepancies; so that no star may be entered in the catalogue without having been made the subject of observation of at least twice, and each time on different occasion, page 8 by a different instrument and observer. In addition to this, the plan, as originally designed, contemplates measures of distance and angle of position upon all double, or multiple stars, acurate drawings and descriptions of all clusters and nebulae.
No Astronomical work on such an extensive scale has ever been executed or attempted. The value and importance of it are manifold, but difficult of full estimation.
The intention is to make a contribution to Astronomy worthy of the nation and the age, and so to execute the undertaking, that future astronomers in all time may say of it, such a star was not visible in the heavens at the date of the Washington Catalogue, because it is not there, and such a star that is now missing, was in the heavens because it is in that work.
Such, at least, is the point aimed at. How far we shall fall short of it remains for results to show. These are the principle subjects of observations. There are many others; but to recount them would make my letter tedious, I therefore pass them by.
Great undertakings such as is this Catalogue, whose value and importance are confined to no country, and limited to no age, are beyond the power of Astronomers working single-handed. They require a large force and abundant facilities, such as individuals cannot afford, and therefore fall pecularily within the provinces and duties of government. It is to be a contribution to science worthy of a great nation. It is to exceed beyond the age in which we live and reach posterity with lasting benefits. If, therefore, a grand Catalogue be undertaken at all, no labor should be spared for giving it weight and authority in all time to come; all facilities, means and appliances should be afforded the Observatory, which are calculated to give useful embellishment to such a work, to impart interest, or add to its value. To make it complete researches in the higher parts of physical Astronomy are wanted. These cannot be conducted in the manner most satisfactory to the world and credible to the nation without the aid of a more powerful Telescope than which the Observatory now has.
There is a strong and commendable feeling of national pride among the people of the United States. Whatever the country undertakes to do, they desire to see it well done. I have reason to believe that this feeling as strongly with regard to the Observatory, now that it is in operation, as it does in regard to any other subject whatever. I refer with pride to this trait in the character of the American people, for it causes them to desire never in National undertakings to be behind other countries.
Accordingly, I have consulted the most celebrated artists of Europe as to the cost and size of the largest Refracting Telescope equatorially mounted, that can be made. The largest Telescope of the kind in the world, and the largest that it has hitherto been thought possible to construct, has an object glass of but 18 inches in diameter. That of this Observatory has an object glass of but only 9 inches, and there are two others in the country nearly, or quite double the size of this.
The celebrated opticians and principal makers of refracting Telescopes, Merz and Son of the Fraunhoffer establishment, who have been consulted on the subject, are willing to risk their character and reputation as the most renowned makers in the world, upon an object glass of 24 inches clear aperture. They have made the liberal offer of such an instrument for $120,000. And it will require four or five years to complete it. I hazard but little in saying that a Telescope of this description, made with the usual skill and success of these celebrated makers, would surpass all others in its astronomical performances. It would be regarded by practical Astronomers and those engaged in the researches of Physical Astronomy as the most superb instrument in the world. And what would be the cost of such an instrument to the people of the United States? Only a hald of a cent per head.
They are enlightened, free, and intelligent, and would they, think you, when reminded of the practical importance of Astronomy in the daily affairs of life, whether, as between man and man, or nation and nation grudge an appropriation for such a purpose?
There is no department of science which is more intimately connected than Astronomy, with the interests whether of government or people. By Astronomy the length of the year is established, the rising and setting of the sun are calculated, and time itself, in all its relations, is measured, fixed, or determined. The man of business, when he looks at his watch for the hour, is as much indebted to Astronomy for the ability punctually to fulfill his engagements as the farmer punctually to fulfil his engagements as the farmer, when he consults his almanac for the phases of the moon.
When a boundry line is to be established between this country and a neighboring, or between State and State of the Confederacy, it is done by Astronomy. The latitudes and longitudes of lines and points, on the earth are determined by the positions of the stars, or other bodies as we find them recorded by European Observers. If there be mistakes in the declinations which they assign to stars, there will also be like mistakes in latitude which we determine from them, and it would be quite as consistent, with true national self-respect, to send for European surveyors to run our boundry lines, as it s to look to European Astronomers to determine for us the true positions of the stars, without the positions of which stars, those boundries could not be run.
Without the guides and help of Astronomy which have been kindley and gratuitously furnished by other nations, we could have no navy, no ships, no commerce, or if we had our ships could never venture across the ocean or out of sight of our own shores.
But for the Nautical Almanac of England, or other European countries, and the labors of their Obseratories and astronomers, the American ships, now abroad, could not find their way home.
But for the principles of practical Astronomy, the metes and bounds of landed estates could neither be recovered nor preserved. It is true the lines of a survey are run by a compass, but the compass is not true, nor stable. Its errors can be detected only according to astronominal determination.
I have a letter, now before me, from a surveyor in a neighbooring state, that the landmarks of a survey run a century since, and which he has now to run over, have been obliterated. But he states his compass-courses and asks for information to enable him to determine what they now should be, to reproduce the same lines. Similar calls are, by no means, unusual. Considering their frequency and importance, I may be excused for suggesting here a law in every state, requiring for the benefit of every state, that hereafter, all deeds of conveyance in which the meters and bounds of real estate are set forth or described, should expressly state the variation of the compass at the time of the survey.
We take a weight, or measure a rod, and call the one a pound, the other a yard. But use, decay, time, and heat, produce their effects, and these measures are altered, changed and lost forever. If preserved in their tangible shape, they are no longer of the same value. But Astronomy furnishes and invariable unit for weight and measure which never changes; and nations are continually in the habit of consulting it for the benefit of their people. Every person, therefore, who buys and sells by just and lawful measure, is enabled to do so only in consequence of Astronomical determinations — so intimately are the principles of this science interwoven with of men and nations, in their political, social, and civil relations.
The reasons and the considerations which call for the establishment of national standards of weights and measures, call with like force propriety and urgency for a national standard of Astronimical results. These results are comprehended in the term, and included in the work, styled The Nautical Almanac.
The advantages and importance of such a work are obvious. It is unnecessary to point to them here.
I will merely mention that the Nautical Almanac should be computed and published, at least three years in advance, so that ships, departing on long cruises, may be furnished with a copy. That it is a work which requires much labor and great care in the preparation; for any, the slightest error or mistake, may prove disastrous both to property and life in all parts of the world. The superintendent of the Observatory could not undertake to superintend the Nautical Almanac, in detail without wholly neglecting his other and equally important duties. He might, indeed, have the general direction of it, so far as to say what it should contain, from what sources the materials to be embodied in it should be obtained, and what tests, examinations and proofs it should undergo in the preparation, etc. But there should be a special and subordinate Superintendent of the Nautical Almanac, whose duties should be confined to the details of the work and to nothing else. He will require the assistence of a small corps of computers; for every calculation should be repeated at least twice, and by at least two computors, each working independent of and without the knowledge of the results obtained by the other.
In the foregoing account, are included a portion of the duties performed at this office and mention has been made of but a part of the force engaged
The Observatory is, literally, also a “Depot” of charts and instruments for the Navy.
Here charts are purchased, prepared and distributed; nautical books supplied, instruments, etc. furnished to our public vessels. Before a chronometer is purchased here for the Government, it is taken on trial for a year, during which time it is carefully compared with a standard clock, that a record may be kept of its performances, which record is required with the utmost niceity and embraces a hundredth part of a second. There are some sixty or eighty chronometers alone in the office whose rates are kept with such care. Besides these there are numerous other instruments which demand much attention.
There is, also, much hydrographical duty to be performed: Charts are to be corrected or compiled; and the undertaking has been commenced here of preparing “wind and current” charts of the three grand oceans, viz : The Atlantic, Pacific, and Indian
These charts are intended to generalize experience of navigators in such a manner that each may have before him, at a glance, the experience of all. The track of each showing the time of the year, the prevailing winds and currents encountered, with all other information obtained is projected on the charts. The first sheet, of which there are 8, of the Atlantic, drawn by William B. Whiting, Lieut. U. S. Navy, has already been published, the other 7 are in the hands of the engraver.
I send, herewith, a copy of sheet 1, and ask the favor of you to accept it. It relates to the Gulf of Mexico, and you will observe that it exibits the prevailing currents and winds of that region at a glance, and with a perspicuity, certainly and generalization that written accounts cannot give.
Books, if I may so say, impart information through the ear — these charts through the eye, and therefore in a manner and form much more condensed and available.
You will observe, by this chart, that the general currents in the Gulf of Mexico are almost as regular in their courses and as sharp in their outlines as is the Mississippi river itself. So that, with this sheet as a guide, a vessel by turning a little to the right, or a little to the left, according to its indications, may convert an unfavorable into a favorable current, and the reverse.
Another important result to flow from these charts is the removing of all doubt of those “Vigias,” including rocks, reefs, and shoals, which by reason of the uncertainity as to their existence and position, disfigure the best general charts, harass navigators, and stand in the way of commerce.
There is, also, a regular series of Meteorlogical Observations kept here. For this purpose, there is always an officer kept on duty, night and day, who is also charged with subsidiary computations in connection with Astronomical results. Besides these duties there are various others which, taken in the aggregate, give, with the above mentioned, constant employment to the three Lieutenants and seven passed Midshipmen, who have not been named.
These officers are Lieutenant Joseph C. Walsh, in charge of nautical books, maps, charts, and instruments. It is his duty, also, to keep and repair for examination, records showing the performance of each chronometer, and the condition of every other nautical instrument, book and chart, with reference to its fitness for service.
Lieutenants D. D. Porter and William B. Whiting find constant employment as Hydrographers. They are especially engaged, at present, with the “wind and current” charts already alluded to. The materials for which are obtained from the Log Books of the Navy.
The officers charged with the Meteorological Records and Observations are, Passed Midshipmen
Joel S. Kennard, Samuel B. Carter,
Geo. B. Bissell, William H. Smith,
Henry K. Davenport, Samuel B. Elliott,
George M. Ransom
These officers are also employed as computors and as assistantsin preparing the Astronomical Observations of 1846 for the press, and with various other duties of minor importance too tedious in their details for their description here.
With high considerations of respect and esteem, I remain, very truly, your friend and obedient servant,
M. F. Maury, Lieutenant U. S. Navy
Hon. John Q. Adams