The Sir William Osler Collection, distinct from the Bibliotheca, is an extensive archival holding of Osler's correspondence (including eighteen hundred original letters), daybooks, accounts, engagement books, legal documents, book invoices, membership certificates, notebooks, lectures, addresses, newspaper clippings, photographs, books with manuscript additions, and miscellaneous loose items formerly inserted into individual books in his library. The collection also contains various family papers, including correspondence of Lady Grace Revere Osler and Edward Revere Osler.

These McGill papers are entirely concerned with his property and estate. They comprise legal documents and copies of letters (some in McGill's hand) concerning his land holdings on St. Paul St., Montréal, in Stanbridge, and in Detroit. McGill's cash book, 1809-1815, and copy by W.D. Lighthall of a deed of conveyance to McGill of some land formerly occupied by the city fortifications, 1805, are also included, as is a blue-print and sketch by W.D. Lighthall of the site of McGill's St. Paul St. house. Estate papers comprise a probate of McGill's will, copied by Alice Lighthall, and his executor's cash book.

Included is the constitution, by-laws, and minute books covering 1922-1940. Approximately one half of this material consists of membership cards recording the name, rank, degrees, and publications of members from 1920 until ca 1970. There are also membership lists for various periods including the founding members and lecture lists, ca 1930s. The secretary's files, covering the period 1963-1969, contain files on dues collected, expenditures, membership (nominations, transfers, correspondence with members), the national convention, and chapter meetings. Financial transactions from 1939 to 1946 are recorded in the treasurer's account book.

The company's records contain administrative, financial and publicity material. The administrative series comprises the minutes of the directors from 1929 to 1955 and of the executive committee from 1949 to 1956. An engagement book records contracts between the company and its employees, 1902-1906. Henry Morgan's business correspondence covers the period 1847-1850, and includes a few personal letters to his brother James. Financial records cover both internal operations and stock transactions. The former are documented by an account book, 1845-1848; ledgers, 1870-1889; and diaries, 1884, 1936; the latter by lists of stock holders, 1954-1960; and records of transfers of Morgan's common stock, 1954-1961. Also included are files of invoices, receipts and cheques, 1846-1852. Publicity materials largely centre around anniversaries. Scrapbooks of newspaper clippings, other printed materials and photographs cover the years 1936-1945, culminating in the company's centennial, for which a typescript history was prepared.

The fonds reflects the scientific and literary outreach activities of the Montreal Natural History Society over the course of its existence and contains correspondence, minutes, financial records, council and committee reports, membership lists, donation lists, catalogues of holdings, newspaper clippings, lecture advertisements and weather maps. In addition, the fonds includes reference material to other societies and information regarding the publication and creation of the Canadian Naturalist and Quarterly Journal of Science, Canadian Naturalist and Geologist and the Canadian Record of Science.

The fonds is composed of the following series: 1) Accounting Records (1860-1917); 2) Administrative Records (1833-1887); 3) Catalogues (ca.1829-ca.1925); 4) Correspondence (1871-1896 with gaps); 5) Essays and Lectures (1829-1852); 6) Minutes (1827-1832,1844-1923); 7) Montreal Microscopical Society (1884-1906); 8) Reports (1828-1881 with gaps); 9) Weather Maps (1895-1897).

Collection consists of six account books dating from the 1830s to the 1860s, including ledgers and daybooks, used and kept primarily by Enoch Curtis for his leather tanning business. There are also some loose accounts and notes on small sheets of paper. The ledgers use a single-entry bookkeeping method in £sd. They are organized by individual merchant account, with records of debits (purchases or expenditures made) and credits (payments or goods received). Parallel underlining and Xs indicate when an account has balanced. The collection also includes some records related to Stella Curtis from the 1890s, including one letter and two sheets of math problems marked Clarenceville Model School.

The greater portion of these records consists of journals, cash books and ledgers recording purchases and sales, 1822-1898. Also included are formula and prescription books, catalogues, price lists, company releases, 1948 and 1952, and a genealogy of the Lyman Family in Canada.

The official records of the Montreal Ladies' Educational Association comprise minutes of the General and Executive Committees, 1871-1885; an account book, 1871-1885; a fee register, 1880-1885; a list of students of the M.L.E.A. and after 1885 of McGill, 1881-1890; a register of certificates granted, including comments on the student's performance, 1871-1885; and printed prospecti and annual reports. A 'Register of Teachers', 1871-1881, contains advertisements for school teachers and governesses.

McDonald's correspondence, 1791-1860, mostly concerns business and property matters, but also includes personal correspondence. There are statements of account with McTavish, Frobisher & Co., 1799; with McTavish, Fraser & Co., 1803-1804; with McTavish, McGillivray & Co., 1808-1809. There are two volumes of autobiographical notes assembled in 1859 and covering the period 1791-1816.

There is a second copy of the autobiography, probably transcribed in the late 19th century. Written on the front fly leaf is the name: A.E. MacDonald. It has 63 leaves, and there are minor textual variants.