Unable to determine, whether the Application I contemplate to make, should be addressed to your Excellency or to Congress, I conclude it most proper to submit it to you, and to request that you will favour me with your opinion what steps it may be most prudent to take on the occasion. I am reduced to this difficulty, by considering whether some particulars I shall state, in order to illustrate the merit of the Application, can be communicated to Congress, without endangering the advantages which the Public might derive from them, were they to be kept Secret in the hands of Government.

when the merit of a man’s claims for Services rendered the Public, are to be estimated from the utility and importance of the Services themselves, and the disagreeable circumstances to which the Party was subjected in performing them, a plain Narrative of facts, seems to be the most likely method to enable one to judge, whether his claims on the Public are well or ill founded.

A Medical education in the Schools of Edinburgh, London, and Paris, during a period of between 7 & 8 years; frequent opportunities of seeing sundry Mechanic Arts practised in the Manufactories of England in the Course of a long residence and much travelling in that kingdom; and several voyages across the Atlantic: these concurring circumstances suggested to me some new ideas relative to Politics & Naval War, and Enabled me to carry them into practice.

The curious Experiments on Sympathetic Inks, fluids with which if one writes on the whitest paper the Letters immediately become invisible, are generally known; and so is likewise the facility with which the writing with any one of them may be rendered visible. For this reason I presume the subject has been considered as a matter of mere Curiosity & Entertainment, and has never been applied to any Use in Politics or War. When the Affairs of America, previous to the commencement of hostilities, began to wear a serious aspect, and threatned to issue in Civil war, it occurred to me that a fluid might possibly be discovered for invisible writing, which would elude the generally known means of detection, and yet could be rendered visible by a suitable Counterpart. Sensible of the great advantages, both in a political and military Line, which we might derive from such a mode of procuring & transmitting intelligence, I set about the work. After innumerable Experiments, I succeeded to my wish. From England, I sent to my brother John in New York, considerable quantities of these preparations. He furnished Silas Deane with them when that gentleman first went to France. When Mr. Deane was in Paris, he writ to me in London, requesting further supplies of them, which I accordingly sent him. In the course of the War, General Washington was also furnished with them, and I have Letters from him acknowleging their great Utility, and requesting farther Supplies. Gordon in his history of the Revolution relates the fact, but without mentioning the author of the contrivance.

By means of this mode of conveying intelligence, I transmitted to America the first authentic account which Congress received, of the determination of the British Ministry to reduce the Colonies to unconditional submission; the Ministry at the time concealing their Design, and holding out conciliatory measures. My method of communication was this. To prevent the suspicion which might arise were I to write to my brother John only, who was a Member of Congress, I writ with black ink a short Letter to him, and likewise to 1 or 2 other persons of the family, none exceeding 3 or 4 Lines in black ink. The residue of the blank paper I filled up, invisibly, with such intelligence and matters as I thought would be useful to the American Cause. All these Letters were left open, & sent in that condition to the Director or Secretary of the General Post Office, with a Letter insinuating that I thought it could not be the intention of Government, in their restraining Laws, to put a stop to family intercourse; and therefore requesting the party to read over the Letters, and if nothing improper appeared in them, that he would permit them to pass in the Mail to New York. They passed accordingly, and on their arrival in New York were sent into the American Lines. In this invisible writing I sent to Franklin & Deane, by the Mail from London to Paris, a plan of the intended Expedition under Burgoyne from Canada

Notwithstanding the pains I took to be satisfied of the difficulty of rendering visible what was written with this fluid, I was not insensible that Accident might produce that Effect: nor was I insensible of the perilous situation in which I placed myself. I persevered in this Mode of communication about three years till I embarked for America. Nothing happened in Europe all that time that endangered a discovery; but in America, a circumstance occurred, which had like to have exposed the whole business. My brother, with a view to do justice at a future day to my zeal and services in the Cause of our Country, preserved all my Letters. When Lord How arrived at Staten Island with the Troops from Boston, my brother sent those Letters to a place of safety, as he thought, in the Jerseys. In that Campaign, the British Troops marched within seven Miles of the house where they were deposited. To prevent the like danger for the future, he took the earliest opportunity to get the Letters & burnt them. Had those Letters, all written with my own hand, subscribed with my name, and made visible, fallen into the hands of the Enemy, there is no difficulty to judge what would have been my fate.

I attempted to return to America the latter part of 1775, with a view of executing what I then deemed, and still deem, some considerable improvements in Naval War; which I thought, and still think, would have enabled us to put an end to the war in a short time. For a Sketch of those improvements, I refer to a little Pamphlet accompanying this Letter. At the period just mentioned, there was no intercourse between Britain and America except by Ships of war, & vessels employed by Government; and Orders were given that no passengers should be taken on board, except such as had permission from Government to embark. I applied for such permission but could not obtain it. My correspondence with the British Ministry on that occasion will speak for itself. This application consumed so much time, as to preclude the possibility of getting to the Ports in France before the vessels destined for America would sail from thence. The following winter I went to France, in expectation of getting a passage from thence, but soon after my arrival in Paris, I was told by Mr. Deane, that all the vessels intended that season for America had already sailed, though as I afterwards learned, the Ship that brought over the Marquis La Fayette, and one or two more vessels, were at that very time still in Port. For this extraordinary conduct in Mr. Deane, with whom I had not the least misunderstanding, I can assign no other reason than he knew I was sensible of a fraud he was committing on the United States, and that he may have thought my arrival there would not conduce to his honour nor interest.

In July 1778 I arrived in Boston from France. I soon determined to lay out the property I brought with me for my subsistance, in the purchase of Continental Certificates which bore interest payable in France. Mr. Andrews, the Clothier General in that City, represented to me that he was in great want of Cash to carry on the business of his Office, that I could procure the like Certificates in Philadelphia where I was going with Dispatches for Congress, that as he had an opportunity of making an advantageous purchase for the Continent, it would promote the public service if I would Let him have my money, and take his Draft on Mr. Mease, Clothier General, in Philadelphia, who would pay it immediately. On these considerations I Let him have 20,000 dollars, the money being at that time 3 for 1. Not suspecting that any thing could happen in Philadelphia to detain me in that City, I made an Engagement in passing through the State of New York, to return there without loss of time. On my arrival in Philadelphia, Mr. Mease was not in Cash to pay the Draft, owing to a misunderstanding between Congress & him. Thus disappointed, I was obliged to remain 3 weeks in Philadelphia, a fortnight longer than I intended to stay there, waiting a settlement of the business. A warrant of Congress for 20,000 dollars was at last delivered to me, but having no time to dispose of the money as I had intended, I did not draw it from the Treasury, but depositing the warrant in the Loan Office of Philadelphia, I immediately set out on my return to York State. Subsequent Engagements in public business, the successive depreciation of the Currency, the impossibility of investing my money in such Certificates as I originally intended, hindered me from receiving the money on the Warrant bill October the 8th. 1779, when, driven by necessity, after having in vain previously endeavored to dispose of Landed property to raise money for my subsistence, I took up the Warrant, received the nominal Sum, exchanged the bulk of it at 130 for 1, and was even obliged to sell my gold watch to pay some debts before I could leave Philadelphia.

Before I say more of this money transaction, it may not be amiss to state a fact which will give you some idea of the importance that has been attached to the Naval improvements alluded to. Without that circumstance however, I feel a pleasure in thinking, that the Merit of them is now to be judged of by a man who possesses a mind that can soar above vulgar Errors & prejudices; who is sensible of the blind and obstinate attachment which the bulk of mankind have to long received opinions, not only in Science, but even in the Mechanic Arts. I am persuaded that were you to bestow a little reflection on the common Mode of mounting Cannon in Ships, and conducting Naval war, you would consider the present state of those matters as a signal instance of the prevalence of old habits over common sense. But to the Fact, when I was in Holland in 1782, I suggested to the Duke De la Vauguion, the french Ambassador at the Hague, the Outlines of these improvements. On his return to Versailles, he mentioned them to the Marshel de Castries, Minister of the Marine; and I was immediately sent for from Holland. At my first interview with the Marshel, after much enquiry on the subject, he candidly observed that, though he was Minister of the Marine, he did not pretend to understand the business in detail, but that on every matter to which he was not competent, he took the opinion of men of knowledge & skill in the branch in question, and governed himself accordingly; and that he must act in the same manner in regard to the matters I had mentioned. The Result was, that an Expedition, founded on the proposed improvements, was determined upon, if the negotiations then pending should not terminate in peace.

In the very disagreeable situation in point of pecuniary circumstances to which I was reduced, as before stated, I applied to Congress in September 1780 for relief. That Body Resolved, “that it was inexpedient to grant me relief. Some of the Members, sensible that my Loss and subsequent distress were owing to the delay that was used in paying the Draft, deemed that Resolution very injurious to me; but observed that in the present state of things it could not be avoided; for were Congress to make up the depreciation to me, they would soon be crowded with Applications from people whose Cases, though seemingly similar with mine, were nevertheless very different. It was said, that if I would mention any considerable service which I had done the Cause, and so discriminate my Case from those of other people, Congress could, on such ground, indemnify me without giving umbrage to any One. I could have replied, & called General Washington to witness the Truth, that at that moment and for a long time before, he had Agents & Spies in the Enemies Lines, who were continually conveying useful intelligence to him by means furnished by myself, and which no other person could supply him with; and that intelligence could not be obtained from the British Lines in any other way with equal facility, safety, and expedition. Such a communication would have answered my purpose, but would have destroyed the future utility of the invention. I could also have availed myself of the Naval improvements before mentioned to surmount my distresses, by engaging a Merchant or two to equip a private Ship of war on that plan, but as such a step would have disclosed those improvements to the Enemy, who might employ them against our Allies and thus injure ourselves, I declined to recur to so dangerous an Expedient.

I now Sir propose to appeal to the honour and equity of my Country. The situation of my Affairs would not permit me to make the application at an earlier period: nor will my circumstances allow me to dispense with it. Were a Calculation to be made only of the real value I received for the 20,000 dollars advanced for public use, and of the interest that has accrued on the Residue to this time, it will, I believe, appear that, exclusive of any gratification for Services rendered, there are due to me about 20,000 dollars. I have the honour to be, with the utmost respect,

Sir Your Very humble Servt: