Pernambuco, Brazil: [self-published] April 6th, 1837. First Edition. 3 1/4 x 5 inches when folded. One sheet folded in half, with the letter written on two pages and address on a third. Then folded for mailing. Folds and staining. A stampless letter from a Nath. S. Osgood to Col. S. Wilcox updating him regarding putting into port in Pernambuco, Brazil in order to obtain a new mast and the challenges faced therein. His next stop is Mauritius. A transcript and some basic research we've done on the people involved follow. Fair. 
The writer Nath. S. Osgood is probably:
CAPT NATHANIEL S OSGOOD Joined the Marine Society Nov 26 1829 Died May 2 1881 aged 80 years Secretary from Nov 30 1848 to Nov 28 1867 Vice President from Nov 30 1876 to Nov 29 1877 President from Nov 29 1877 to Nov 27 1879 Capt Osgood was born April 23 18O1 His first voyage to sea was as supercargo of the brig Herod John Wills master bound to Calcutta next on the ship Potomac Caleb Norris master making 13 voyages to Batavia and Ceylon He made three voyages carrying provisions in the Greek war covering two years each He gave up his sea life in 1844 and was appointed to a situation in the Custom House at Newburyport and was always greatly interested in the Marine Society and always worked for its interest. (History of the Marine Society of Newburyport, Massachusetts)
Col. Jonathan S. Wilcox was of Madison Connecticut, and a member of the local militia.
The Duan, a brig of Beverly Massachusetts which carried a previous letter to this one, was involved in the slave trade and often visited Rio de Janiero. It is most likely that the letter was written from Pernambuco, Brazil, and picked up by the Duan as it put in along the coast of Brazil.
We find in the Sept 1, 1837 Government Gazette By Cape of Good Hope (Colony) a notice that the Catherine Wilcox an American schooner NS Osgood from Mauritius Aug 5 to New York listed. Cargo hides &c Put in refreshments, Isaac Chase USC Agent, so apparently the trip continued and the ship's name known!!
Our best attempt at a transcribing the letter follows:
Pernam buci 6th April 1837
Col. S. Wilcox:
Dear Sir. I wrote you up to the 24th March by the “Duan” of my being obliged to put into this port for a new mast &c &c and that I had succeeded in getting one from ?oo? on condition of replacing it in 6 months. This was done by the authorities here and as a particular favor to the American consul – a vessel having since arrived with spares I had hopes of getting a mast from her to replace the one I had from the arsenal – but the consignee objected to selling one spar and that the best of the lot. The consul having given bonds to replace the mast and is being quite uncertain whether it would be in your power to send so large a spare to this country. I have thought it most prudent to settle here for it & for the sum of 500 mullre (?) as Mr Ray has agreed to assume the responsibility of getting one here in the time specify'd as the last mast which was sold here was much smaller and brought 500 $ I cannot say it is an unreasonable price as the mast we had was 72 feet by 20 inches at the butt.
I am obliged to bottoming (??) the schr (?) to reuse finding the expences being about 1500 millenau(?) 500 of which I have paid from proceeds of damaged goods sold, & for the balance [illegible 1/2 line] 500 being funds of R B Forbes Esq. have drawn a bill on you in his favor for t amount of 60 ?enys eight as the present rate of exchange.
The vessel being now fitted as well as she can be I shall sail (th) night & hope I may reach Mauritius without further damage. I hope I may not have to get any new sails at Mauritius but I find the main sail very much worn – the vessel is so very labour some that sails wear out three times as fast as I ever knew them before to.
I shall forward one set of accounts to ?? of Mr. Walter R Jones Vice Pres of the Atlantic Ins office to be sent to you as the bottom ?? bond will be at a monthly maritime interest. I hope it may be paid as soon as presented – you will see my letters to Mr. Jones on the Subject -
I can only say further that in all this business I have endeavered to do what was right and hope what I have done will meet [half line illegible]
In the mean time I remain
Nath S. Osgood
The letter is hand Addressed to:
Col. Jonathan S. Wilcox
With red stamp “SHIP” above that.
The postal cancel is hard to read, our best guess is:
with handwritten '14 1/2' upper right corner which we believe was the rate of postage.