Series consists chiefly of 38 manuscripts related to the North West Company. Among the Masson manuscripts there are other series of letters; as well as journals kept by North-Westers and various business documents. Some of this material exists as originals; others are contemporary copies - the George Keith letters for example are contemporary copies on paper watermarked 1827. The collection also includes some duplicate texts - contemporary copies or later nineteenth-century copies that in some cases represent edited versions of the texts. Samuel Wilcocke's account of the death of Benjamin Frobisher exists in a draft original (or contemporary copy) and in a late nineteenth-century clean copy. Of course Benjamin Frobisher did not die in the dramatic circumstances as recorded by Wilcocke, but peacefully in Quebec City in 1821.