FORT LAFAYETTE, October 6, 1861.

E. M. ARCHIBALD, Esq., British Consul, New York.

DEAR SIR: I am a native of Canada, the son of a British soldier; have been a resident of the United States about twenty- three years; have never been naturalized or declared my intention of becoming an American citizen. Mr. W. H. / Duane, 58 Maiden Lane, can assure you of above facts as much as anybody I know of. I have written him to call upon you, and if it is not objectionable would be very much obliged if you would allow him to read this letter.

I was arrested in Philadelphia (where I reside to do business) on 20th of September and brought here Monday morning, 23d. A monstrous invention, purporting to be an account of my case, was published in New York Herald, 24th. I was reluctant to trouble you, as I thought that the Governmetn would release me without and had been led to suppose so by the officers who arrested me. SO after waiting a week I directed a letter to Honorable W. H. Seward, Secretary of State, at Washington, onOctober 1. Not having received any reply I now appeal to you, ad beg in as concise a way as I can to submit all the facts in my case, pr3emising, however, that I have never had any distinct cahrge made aginst me; that I was in Philadelphia prevented from holding communicaitonwith any one; was refused counsel or appeal to British consul, and that a young man in my office was kept in prison as I was informed merely for having my card case which contained my consul's certificate, which I suppose he was carrying to my attonry. The U. S. marshal showed me this certifdicate in his own possession; refused to give it up to me, so that he had every resson to know that I was a British subject.

I had been thrown out of business by these troubles, was comparatively idle when some two or three months ago I was offered a commission for buying India- rubber overcoats, blankets, &c., Colt's pistols, percussin- caps, army cloth and other army goods by a merchant of Baltimore who was not familiar with the trade (Mr. James M. Haig). He told me there was a good demand for such goods inhis place and in Washingtona and assured me they were for no disunion purpose byut for a legitimate Union trade, which to me seemed very p; ausible, and I undertook the commission and came to new York to byuy the goods, which I could not get in Philadelphia.

Up to this date (which I cannot state) I had herard of no prohibition of forwarding any kind of goods to Baltiore; had heard of some pistls having been stopped in New York but immediartely sent on agin, but still when there in New York I wrote to Secretary Seward from Sweeny's Hotel that I had a commission to buty army goods for a Baltimore house whichI was then executing and whichI would ifll and forward if he did not advise me to the contrary and gave him my Philadelphia addresss. I got no a nswer and bought and fowarded goods to the valu3e I think of $3,700. I am since assured by mr. Haig that these goods were all sold in a legitimtate and proper manner and that he really wanted them for Union purposes. However, that trade was finished and is I believe a loyal one to say the least or worst of it. Some time after this same gentleman proposed I should buy more for hima and from the magnitude of his talk and some memoranda I concluded that the trade was illegitimate. Iought to have stopped here but judging that this propoosition was atually from headquarters in the Confederate authorities I foolishly deemed that I could be of service to the OGvenrment by encouraging it. Consequently I did not