This lovely example signed "Parkinson & Frodsham, London" also dates circa 1850. Note the addition of a handle and horizon shades on the instrument itself. As for accessories, a peep sight and telescopic sight have been added. At this point, the only thing that differentiates the octant from a sextant is the arc of its scale and lack of a vernier magnifier. The existence of the "keystone" box helps in pointing at its mid 19th C. or earlier origin. The trade labels in the lid are those of Thaxter & Son and Aaron Breed, both of Boston. Thaxter's were the American agents for Parkinson & Frodsham during the first half of the 19th C. Original trade labels are an excellent tool in helping to date the period of an instrument. (Collection West Sea Co.)