[Navigation]
A manuscript navigation treatise by Joseph Barker, dated 1759, consisting of handwritten geometric instructions for finding positions and variations at sea. Its pages present hand-drawn circles with chords, arcs and lettered points, with explanatory text beside and below each diagram.
![Picture 1 of 8 from [Navigation] (1759), leaf 33](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-33-0.webp)
![Picture 2 of 8 from [Navigation] (1759), leaf 45](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-45-0.webp)
![Picture 3 of 8 from [Navigation] (1759), leaf 73](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-73-0.webp)
![Picture 4 of 8 from [Navigation] (1759), leaf 92](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-92-0.webp)
![Picture 5 of 8 from [Navigation] (1759), leaf 103](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-103-0.webp)
![Picture 6 of 8 from [Navigation] (1759), leaf 115](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-115-0.webp)
![Picture 7 of 8 from [Navigation] (1759), leaf 143](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-143-0.webp)
![Picture 8 of 8 from [Navigation] (1759), leaf 157](https://img.insideoutlibrary.com/img/200/ia-navigation00bark-157-0.webp)