I recieved last night your favor of the 13th. with regard to the papers which respect the claim of Maryland to the South branch of Potomak, whose titles are particularly mentioned by you as extracted from the Notes on Virginia. I can say no more than is there said. the source from whence the papers are to be obtained is always stated there when known to myself. I think the Commissioners should procure the following papers.

no doubt that all these papers on the petition of Ld. Fairfax for the establishment of his boundary are to be found in his land office. it is impossible they should not have been recorded & bound up in a book by themselves. should they be lost, they ought to be sought from England. I well remember to have heard my father explain the experiments & principles on which the Commissioners decided that the Northern was the principal branch of the Potomac. the very question now called up by Maryland was the one decided by these commissioners. I have a copy of their survey, which was engraved and struck off on a scale of 5. I. to the degree of latitude. it is exactly copied in Fry & Jefferson’s map, Ld. Fairfax having furnished them from his land-office all the materials for the country between the Potomac & Rappahanoc. the degrees & minutes are laid down in the margins of this survey.

The proceedings on a suit in the Chancery of England between Lord Baltimore & Penn are interesting in this case. they are collected in the form of a preface to the Laws of Pensylvania, as they stood before the revolution. this volume ought to be procured. they took [place?] in 1680. & 1681. under this decree in Chancery Mason & Dixon were sent over to run a boundary between Pensylvania & Maryland from the Delaware to the meridian of the 1st. fountain of the Potomak, and did it with the more accuracy as they were at the same time employed by the royal society to measure a degree of longitude in the same parallel of latitude. it is impossible but that in these proceedings in Chancery will be found the most unequivocal acknolegements by Ld. Baltimore that the branch of the Potomak to the meridian of whose first fountain they run, was the branch bounding his claim. in the 58th. vol. of the Phil. transactions is the report of Mason & Dixon on their operations on this survey. probably that will give useful information. no doubt a compleat record of every paper in the chancery suit can be had from England. the case itself is reported, as to the law questions, in one of the Chancery reports. I believe it is Vezey, but cannot say certainly as I am writing here where I have neither books nor papers. the copies of surveys &c. furnished by Ld. Fairfax to Messrs. Fry & Jefferson were among my fathers papers when he died in 1757. and remained in my possession till they were burnt in the house at Shadwell in 1768. which was the 1st. fountain of the Potomak might have been doubtful in the beginning, but the doubt was settled, and the lines depending on it have been long since located & are attested 1. by the exercise of the rights of soil & jurisdiction by Virginia from the first settlement of the country, & 2. by the non-exercise of the same rights by Maryland, South of the North branch or West of the meridian of it’s 1st. fountain. 3. by the proceedings in Chancery & the survey of Mason & Dixon thereon & acknolegements of Ld. Baltimore. 4. by the proceedings between the king & Ld. Fairfax & the survey [&] final decision thereon. tho’ these are res inter alios actae, yet they are good historical testimony, and history is always competent evidence in disputes between nations. 5. the grant by the crown to Ld. Fairfax & proceedings on that were good or not good. if good on the principle that a subsequent grant could curtail or controul a preceding one, there the question is decided1 by the grant to Ld. Fairfax and the actual location of it. if not good, on the contrary principle that a subsequent could not controul a preceding grant: then the grant of the crown to Lord Baltimore of what had been before granted to Virginia [. . .] and all Maryland belongs to us. if they urge that Virginia ceded the charter boundaries of Maryland2 by her constitution, I answer that her intention as to the limits ceded cannot be departed from, if the claim is built on her cession. that in the relinquishment of her title to the state of Maryland, she meant it3 according to the limits within which Maryland had ever, & then did exercise the rights of soil & jurisdiction, is known to every one who was concerned in the transaction. I drew the clause in the constitution, and know that I had no idea that any other claim was or would be thought of by Maryland. very many members of the convention are still living, and can attest that Maryland as laid down in the maps was the Maryland meant to be4 ceded by Virginia. the decision of Congress on the Connecticut reserve has given great strength to the claims under the oldest grant.

I have with difficulty snatched a moment from other calls to answer your letter, and have most hastily sketched some general outlines, which may suggest to you some particulars in the investigation you are appointed to. I suspect that Colo. George Mason’s papers must contain something valuable on this subject. he had long had it in his head, understood it intimately, and probably collected papers and made notes relative to it. but whether his representatives will take the trouble of making such a search among his papers as might be necessary must depend on the interest your committee can make with them.

Accept my affectionate salutations and assurances of great esteem & respect.