Sundial cannon for latitude 48°-50’-30” N

Sundial cannon which fires at noon, also known as a cannon dial or time gun. The circular marble base (166 mm in diameter) is inscribed with “Cam à Paris”, a maker's mark. In the 1867 catalogue for the Universal Exposition, "Cam, à Paris" is cited as a maker of optical instruments at rue de la Paix, 24. Because of the prestige of Paris instrument-makers in the 19th Century, it was common for them to sign their work "à Paris". When correctly oriented, the sun shining through the burning lens (36 mm diameter) onto the cannon’s touch hole, caused the cannon to fire at noon. The bottom of the marble base has the handwritten inscription “From the collection of John Davis Barnett”. John Davis Barnett (1848–1926) donated 40,000 books to Western University in 1919.