Has anyone besides Egon Pearson accessed William Sealy Gosset's 1904 report "The Application of the 'Law of Error' to the Work of the Brewery"? I guess it's Guinness property, but given its historical significance, it would have been a very interesting read, if someone were to know how to get their hands on it.
Stephen Ziliak, an Economics professor at Roosevelt University in Chicago, has published a number of papers (and a book) on Gosset and related topics. See, for example, this paper, which quotes the 1904 report you mention. In the references section, he cites 15 volumes of Laboratory Reports, which include Gosset's 1904 paper.
The Guinness web site says the archives are open to researchers by appointment; I wasn't able to find a digital copy of that particular paper.