Part 8

During the latter part of the Spanish rule, he was appointed Surveyor General of the District of Natchez. He also served as a representative of the Spanish government in locating the 31° of North Latitude, which was established as the boundary line between the United States and the Spanish possessions east of the Mississippi. As he was never a subject of his Catholic Majesty,[41] these services were strictly professional. The relationship between him and Governor Gayoso was, however, very cordial, as is shown by their correspondence.[42] Upon one occasion,[43] Dunbar presented Gayoso with a costly sextant, which the latter needed in order to complete a course of astronomical observations upon which he was engaged. At another time[44] Gayoso had cause to thank Dunbar for the use of a "famous astronomical circle" belonging to the latter. Gayoso says of this instrument, "it surpassed my expectation,____. Every part is so delicately finished and solidly supported & so well prepared to be adjusted that it would give me courage to make an observation myself. If the instrument was not your own property I would have advised you to make a voyage to admire it. Now I think with your assistance I may with confidence and decency proceed to the demarcation of the Line as soon as I receive orders for the purpose." The sickness of Mr. Dunbar about this time was a source of great concern to Gayoso. In a third letter[45] upon this subject, written two weeks before the work upon the line began, Gayoso expressed some apprehension that, for his sake, Dunbar might imprudently expose himself. When Dunbar was at work upon the line, Gayoso wrote to him as follows: "I congratulate myself for having had the opportunity of meeting with a person so well calculated to fulfill so important a charge for which is required science with every other quality worthy of public trust; you possess them all in a degree to do honor to any country; these are my sincere sentiments."

Dunbar's services on the line of demarcation extended from May 26 to August 28, 1798, the time consumed in surveying the first eighteen miles of the boundary.[46] The preliminary observations leading to the location of the 31° were made in his private observatory on Union Hill.[47] An inundation of the Mississippi prevented the survey from beginning at the bank of the river. The water having receded by the 28th of July, Dunbar began to extend the line to the river from the point of starting, while Ellicott, the American Commissioner, continued his survey to the east.[48] Through this swamp, which was found to be 2111.42 French toises or 2 miles and 186 perches English measure, a trace sixty feet wide was cut to designate the boundary, and posts were put at intervals of a mile.

Dunbar rejoined the American Commissioners on August 20. A few days later he made the following entry in his report to the Spanish government:--"I set out on the 31st day of August bidding a final adieu to the Gentlemen of both Commissions, with whom I had spent three months in a manner highly agreeable to my own taste, and with uninterrupted harmony on my part with every gentleman of both parties, and had it not been that my family and other interests demanded my protection and superintendence, I should have with pleasure pursued this employment to its conclusion."[49] Ellicott, in his report of this survey, published in the Transactions of the American Philosophical Society, says:--"To William Dunbar, Esq., of the Mississippi Territory I feel myself under the greatest obligations for his assistance during the short time he was with us; his extensive scientific acquirements, added to a singular facility in making calculations would have reduced my labour to a mere amusement, if he had continued."[50] The same writer in his Journal, published in Philadelphia, five years after his association with Dunbar, says that he is "a gentleman whose extensive information and scientific acquirements would give him a distinguished rank in any place or in any country."[51] Since Ellicott himself was one of the foremost scientists of his time in this country[52] the value of his estimate of Dunbar cannot be questioned.

A few months after the completion of this important public survey, Daniel Clarke wrote a letter to Thomas Jefferson, in which he referred to Dunbar as "a person worthy of being consulted____on subjects relating to this Country its productions, or any philosophical Question connected with them____For Science, Probity & general information (he) is the first Character in this part of the World. His long residence in this Country, still but little known to men of letters, its Situation with respect to many Savage tribes, some of which lately inhabited the very Place where he resides & where their visages are still perceptible, the extensive Communications with remote parts presented by the Mississippi and concourse of Indians & traders, have given him many opportunities of making observations which may not have presented themselves to others and may not probably occur in future, to these may be added those he has made on the Country itself, its population, manners, Customs of the Inhabitants, the different Changes in their Government for the last 40 years, the Climate, soil & Trade which are but little known abroad."[53]

The manuscript correspondence of Thomas Jefferson, in the Archives of the Department of State at Washington shows that he acted upon this suggestion from Mr Clarke. In this collection there have been preserved fifteen letters that were written by Dunbar.

The first of these in chronological order, bears the date of July 15, 1800. It states briefly that in compliance with the request of a friend in London, Dunbar had prepared certain notes and remarks "made while upon the line of Demarcation." These he sent to Jefferson with a request that after reading he forward them to London. Jefferson, who was then President of the American Philosophical Society and a great patron of science, was so favorably impressed by these notes that instead of forwarding them as directed, he sent them to Dr. Wistar of Philadelphia with a recommendation that Dunbar be elected to membership in the Philosophical Society. On this point Jefferson wrote that he had proposed so many members at different times that he was afraid to add to the number. "Yet," says he, "Dunbar ought to be associated to us. I enclose you a letter with communications of his to Mr. Smith of London which ____will enable you to judge of his degree of science, & therefore, I leave them open for your perusal, & will pray you to seal & send them____to London." Shortly after this Dunbar was elected to membership in this, the most celebrated organization of scientists in the early history of the United States. The fact that only thirteen other Americans were added to this body during the three years from January 1st, 1799 to 1802, gives a proper estimate of the high honor conferred upon Mr. Dunbar. In writing to Dunbar, shortly after this recognition of his scientific attainments, Ellicott says: "If you do justice to your own abilities and observations, you will do credit to the society by your communications."

Before considering the character and extent of his subsequent contributions to science, the notes and remarks referred to above demand consideration. These are contained in his report of the survey to his Catholic Majesty,[54] the Spanish copy of which is in the archives at Madrid. Several years ago it was examined by Alexander Everett, who often referred to it as "a document of rare science and accuracy."[55]

It consists of two parts. The first treats of the mathematical calculations and the astronomical observations made in locating the 31° of latitude and in surveying the first eighteen miles of the line of demarcation. The remainder consists of notes taken at his encampment on the Bluff, in August, 1798. These treat, for the most part, of the vegetable and animal life to be found along the line of the survey, particularly in the swamp of the Mississippi river.

He makes several interesting observations on the red and the white cypress, the former of which he says is the more valuable for strength and durability, owing to its being impregnated with resin. He also observes that the "cypress knees," as they are commonly called, never reach a height greater than the high water mark. In combating the theory of Dupratz that the cypress is propagated from its root, Dunbar says that is "invariably propagated from the seed, which is about the size of a Spanish walnut," and that he has "often observed half a dozen or more young plants produced from one apple, which often coalesce into one and sometimes the greater part perish to make room for their more fortunate brethren." He says of one species of the white oak, that "nature has so ordained that the husk embraces the acorn so firmly that they are not separated by their fall from the tree, by which means this case by its comparatively small specific gravity buoys up the acorn, and being carried along by the various current of the inundation, serves to plant distant colonies of this species." He also gives an interesting account of the cotton tree, the willow and the bamboo cane, the last of which he attempts to classify botanically. He says of the cane: "It produces a very abundant crop of grain, and that only once, for it immediately after perishes, root and branch, it is not known how many years the reed requires to arrive at this state of maturity; if we were to suppose that 25 years were its limit, it must happen that a person who has resided during that length of time in this country and who has visited many parts of it must have seen all the cane that came under his inspection once in grain, and upon the average one twenty-fifth part of all the cane in a large tract of country ought annually to yield a crop, but this is by no means the case, for I who have lived during that length of time in this country and have frequently traversed many extensive tracts of it, have never in any one year seen 1-500 part of the canes in seed of those parts that I have intimately known." He therefore concludes that it must require at least five hundred years for this plant to reach "a state of maturity to enable it to bear a crop of seed."

His description of the ornamental trees of this region is graphic and interesting. No one can read his account of the magnolia tree without being deeply impressed with the fact that he appreciated its beauty. In studying the properties of the poplar, he made a hydrometer of a thin, broad piece of plank of this material, cut across the grain. He "improved its sensibility by boiling it when very dry, in a solution of mild alkali or carbonated potash." He describes many other trees, among which are the dogwood, the redbud, the wild cherry, the horse chestnut and the sweet gum.

He records the observation of a very rare phenomenon, which he saw August 12th, when engaged upon this work. It was a rainbow that consisted of more than a semi-circle, "the vertical point" of which "did not seem more than 8 feet from the eye, although the inferior parts seemed farther removed, which produced an optical deception by giving it the appearance of an ellipsis, the transverse diameter being parallel to the horizon; this perhaps is the first natural rainbow exceeding a semi-circle which has been seen by a human eye, because to produce such an effect from the general idea formed of this phenomenon, the sun ought to be in the horizon to cause the appearance of a full semi-circle exceeded only by the parallactic angle of the elevation of the eye above the base of the rainbow, which must generally be insensible; the above effect however is easily accounted for on Newton's principles[56] from the peculiar circumstances in which I was placed."

He says that the microscope reveals in the water of this part of the country the same varieties of animalculæ which he had often examined in Europe and many new ones, which he does not remember to have seen described by any writer, and which he hopes to find leisure to describe at some future day.

After giving a brief account of some of the wild animals, reptiles, fish, and birds of this country, he concludes with lists of the "vegetable productions of the Swampy Grounds or such as are much exposed to the Annual Inundation;" the "most remarkable vegetable productions of the high lands;" and the "Trees and Plants cultivated by the Inhabitants of the Mississippi territory and by those of the adjoining Spanish Provinces."

As has been noted above, the last ten years of Dunbar's life were devoted almost entirely to scientific research. The value of his contributions to knowledge was widely recognized, and "The Forest" became familiar to the scientific world, though it was sometimes incorrectly placed in Louisiana.

Volume V. of the Transactions of the American Philosophical Society, published in Philadelphia in 1801, contains three articles from his pen, and Volume VI. of the same publication, issued eight years later, contains twelve, one of which was translated into the German and appeared in Gilbert's Annalen of Physics, vol. 31,[57] published in Leipzig in 1809. To this latter volume of the Transactions Andrew Ellicott contributed nine articles, Jose Joaquin de Ferrer, eight, Dr. Benjamin Smith Barton, five, Benj. Henry Latrobe, three, and Dr. Joseph Priestly, F. R. S., three, while to repeat Dunbar contributed twelve. This shows that Dunbar was at that time one of the most active investigators on the continent.

His contributions to the Transactions and his correspondence with Jefferson give a conception of the character and extent to his investigations. The first of these contributions was written June 30, 1800, and treats of the "Language of Signs among certain North American Indians." In this he traces certain points of analogy "between the Chinese written language and our Western language of signs." In both, says he, there are certain "roots of language in which every other word or species in a systematic sense is referred to its proper genus or root." He gives, for example, the sign for water which is a genus and shows that rain, snow, ice, hail, hoar-frost, dew, etc., are species represented by signs more or less complex, retaining always the root or genus as the basis of the compound sign. He adduces other interesting facts from this study of the subject, which cannot be given in this connection.

His Meteorological Observations for 1799, gives unmistakable evidence of his devotion to science. It shows that three times a day, each day in the year, he recorded the temperature and the barometric readings; also the direction and strength of the winds with the state of the weather, and the amount of rainfall together with remarks about the state of the vegetation from time to time. To this he adds a Recapitulation, giving the greatest, the lowest, and the mean points of the thermometer and the barometer, and the amount of rainfall for each month and then for the whole year. The Editor of the publication states in a footnote that "the society have been induced to publish this journal _entire_, as it is certainly the first that has been kept with so much accuracy and attention in that part of the world, and may serve as a standard with which to compare future observations."

In another article, Dunbar gives a "Description of a singular phenomenon seen at Baton Rouge" in the spring of 1800.

His fourth contribution consists in extracts from a letter dated Aug. 22, 1801, which he wrote to Jefferson, relative "to fossil bones found in Louisiana, and to Lunar Rainbows observed West of the Mississippi." In this letter, he referred to an account of "Dr. Hooks' scheme of a telegraphy, in the year 1684," which he intended to transmit to Jefferson, but found himself anticipated in that communication by a paper in the first volume of the London Philosophical Magazine. He also directs Jefferson's attention to "a certain phenomenon at sunset,"--the yellow orange color of the Eastern clouds, which ascends as the sun descends--upon which he makes certain observations and explanations, and suggestions for further investigations by philosophers.

With this letter there was enclosed a fifth contribution to the Transactions. This article is entitled, "Meteorological Observations made by William Dunbar, Esq., at the Forest, four miles east of the Mississippi, in Latitude 31° 28´ North, and in Longitude 91° 30´ west of Greenwich, for the year 1800; with remarks on the state of the winds, weather, vegetation, etc., calculated to give some idea of the climate of the country." In this article he says, "the frequent and rapid changes in the state of the weather in this climate furnish an excellent opportunity of verifying the vulgar opinion of the moon's pretended influence at her conjunctions, oppositions and quadratures; but truth compels me to say (what probably may be said of many similar persuasions) that after a continued and scrupulous attention to this object, I have not discovered any such regularity of coincidences, which might justify the reverence with which those traditional maxims are at this day received." After discussing a method of manufacturing ice by artificial means, he concludes this communication with the following observations on the storms of the Gulf Coast region: "It is evident that the circular course of the vortex followed that of the sun's apparent diurnal motion.--It is possible that if similar observations are made upon all hurricanes, tornadoes and whirlwinds they will be found universally to consist of a vortex with a central spot in a state of profound calm."

Dunbar's next letter that is preserved in the Jefferson Papers is one to John Vaughan bearing the date of March 21, 1802. In this the writer says that he envies Vaughan's "happiness at the discovery of a complete skeleton of a mammoth." He makes some observations on the species to which this mammoth belongs and refers to recent discoveries of a similar nature in the interior of Asia and Borneo. He gives the results of recent geological observations on the nature of the soil and the stratification of the same as shown by the banks of the Mississippi at Natchez; also a discussion of stones, rocks, ores, mineral waters, petrifaction, etc. He requests Vaughan to inform Dr. Bartram that since writing him last, he has made several new discoveries of a botanical and zoological nature which he here describes.

This letter also shows that Dunbar was one of the first Mississippians to resort to inoculation for protection against small-pox. He asked Vaughan to send him some fresh vaccine virus and stated that six children in his own family had never "had that disease, besides a lengthy list of Black people, both young and old." Vaughan complied with this request by sending the virus and asked Jefferson to do likewise, stating that "the Vaccine inoculation gathers strength hourly, _no_ respectable practitioner (of Philadelphia) opposes it."

January 15, 1803 Dunbar wrote to Jefferson: "Bad health which has endured above twelve months has withheld much of my attention from Philosophic objects, a favorable change having lately taken place, I perceive with satisfaction that my mind and body are both recovering their former tone and now again enjoy the pleasing prospect of dedicating my leisure hours to my favorite amusements."

Dunbar's next contribution to the Transactions was entitled, "Abstract of a communication from Mr. Martin Durale, relative to fossil bones, etc., of the County of Opelousas, west of the Mississippi to Mr. William Dunbar of the Natchez," etc. In this account Dunbar, in referring to certain phenomena makes use of the following expression, which has characterized the true philosophers of all ages, "I have never observed them without endeavoring to ascertain the cause of them."

This communication was accompanied by "pretty full vocabularies of the tongues of two Indian nations of that country," to which "was added a sketch of the religion or superstition of these people." In this connection, Dunbar says, "From several other quarters I have used some efforts to draw similar information, but am hitherto disappointed." He also makes mention of a letter which he had just received from Sir Joseph Banks with an extract from the Transactions of the Royal Society.

January 28, 1804, Dunbar wrote to Jefferson transmitting his seventh and eighth contributions to Volume Six of the Transactions, while an extract from his letter was published as a ninth contribution. His seventh article was entitled a "Description of the river Mississippi and its Delta, with that of the adjacent parts of Louisiana." In this he gives a table of the mean altitude of the waters of the Mississippi at Natchez, from the lowest ebb to the highest elevation for the first and fifteenth of each month in the year. It also contains a good account of overflows and some philosophical reflections on the velocity, banks, currents, deposits and depth of the river and the effects of confining it to its channel. In speaking of the overflow lands he says, "although no successful attempt is likely to be made in our day, yet posterity will reclaim" them. He discusses the methods used in Holland and in Egypt, and makes several speculations as to the method that will probably be successful. This sketch, he says, in conclusion, "is the result of occasional observation for a series of years and of scattered information collected from various sources, probably often uncertain, from a cause which is unfortunately, too general; viz: the extreme inattention of persons, even of some education to the most curious phenomena passing daily under their review."

The eighth article was entitled: "Monthly and Annual Results of Meteorological Observations" for the years 1801, 1802, 1803.

In an appendix to his seventh article, he discusses the writings of certain Italian, French and German scientists, giving his reasons for differing with them on certain philosophical questions. His discussion is devoted largely to a consideration of certain laws of hydrostatics.

His "Observations on the eclipse of the sun, June 16, 1806" made in his private observatory on Union Hill, constitutes his tenth contribution to the publication mentioned above. This article gives a vivid account of the excited state of mind with which an astronomer awaits the time when nature affords favorable opportunities for investigating her mysteries. It also shows that this frontier scientist of Mississippi enjoyed in thought, as he could not by personal association, the companionship of the great thinkers of the world. These are his words:

"The moment of the expected impression approached and reflecting that this eclipse was to be seen all over Europe and North America which renders it a very important phenomenon for settling comparative longitudes, I conceived that all the zealous astronomers of both worlds were then looking with me at the great luminary and centre of our system. I kept my eye riveted upon that point of the disk where the eclipse was to commence, with an anxiety known only to astronomers; with the chronometer watch at my ear, I attended to the most doubtful appearances which my perturbation perhaps presented to the eye, and upon every alarm, began to count the beats of the watch (five in two seconds) in order that I might not lose the very first instant of the impression, and I am confident that not one quarter of a second was lost."