Utilizes a white compass card with only an arrow for north and a sparse selection of cardinal points. A movable bearing arrow on the crystal allows you to set a heading and then simply match up north with the pointer. Finer bearing readings were accomplished via a slot on the rear sight (see note below) and a thin vane visible through a transparent window within the cover. Two stops, both manual: a traveling stop via a lever at the lower right and a temporary stop button at the upper right, used to freeze the card after a reading has been taken so the user can read the card.
An entry for (a) Major Mayo was found in the 1901 Hertfordshire, England census: Green End House RG13/2184/7 Edith S Legh, aged 37, born in London Belgravia, wife of Major Legh, not present. With her were 7 live-in servants including the coachman. Only one of these was local - Kate Livings the under housemaid, aged 19, and born in Little Munden.
Lawrence & Mayo was founded in 1877 and is "specialized in the fields of Engineering, Scientific and vacuum instruments."
