Photograph, Mitrailleuse actinometer by William Brennand A photograph of a 'Mitrailleuse actinometer' used by Brennand in his photometric observations of the Sun and sky. Subject: Optics / Photometry / Scientific apparatus and instruments An engraved figure of this photograph was published in volume 49 of the Proceedings of the Royal Society alongside the paper 'Photometric observations of the Sun and sky'. 1890