Sailors could tell the latitude of their ship at sea using a backstaff – also known as a Davis quadrant. The instrument would measure how high the sun was above the horizon to give the ship’s position in relation to the equator.
The backstaff was placed over the shoulders, with the user’s back to the sun. The angle of the sun would be cast through a slit onto a scale on the curved arc at the opposite end.
This version, made of ebonised fruitwood, dates from about 1790. The rear sight and two adjustable sights are removable and also made of wood.
Trinity House and its remarkable historic collections give amazing insights into Leith’s celebrated maritime past. The present building was the Port of Leith headquarters of the Incorporation of Mariners and Shipmasters for nearly 200 years.
This charity was set up to support the needs of injured and retired seamen and their families. Its origins can be traced back to 1380, when it was granted the right to levy a tax known as prime gilt on goods imported into Leith.
Thomas Brown designed the elegant Georgian building that now stands on the Kirkgate. It was built in 1816 on the site of a former Trinity House and hospital dating from before 1550.
Read more on the history of Trinity House [PDF, 8MB]
Maritime treasure house
The layout and historic furnishings of Trinity House still have many unique features that emphasise its former maritime function.
The War Memorial Window designed by W.J.R. Cook in 1933 honours local merchant sailors who died in the First World War. It was rededicated in 1945 for those killed in the Second World War.
The ground floor has a grand entrance and inner hall, with a unique collection of chairs commissioned by the Incorporation from the Edinburgh cabinetmaker William Trotter. Off the hall is the Master’s Room, a cosy space with a fine collection of paintings showing Leith as a busy commercial port in the 1700s and 1800s.
The highlight of Trinity House is the Convening Room on the upper floor, where the Incorporation held meetings around the long mahogany table. Maritime subjects feature in the ceiling’s ornate plaster friezes, and the table now displays a fascinating variety of objects to do with shipping, navigation and the whaling industry.
On display in the room are:
- navigational instruments
- wartime charts
- whaling harpoons
- rare objects such as narwhal tusks
- ship models – ranging from early whaling ships to modern merchant ships
Hung on the walls are portraits of famous mariners and former Masters of the Incorporation – some by the great Edinburgh artist Sir Henry Raeburn. Vasco da Gama Encountering the Spirit of the Storm, a huge oil painting by the Scottish artist David Scott, is also on display.
The vaults below the building, which date from the 1500s, once housed a school for young mariners.
- Date Made
- Late 18th century
- 670 x 365 x 130mm
- Metal/BM Processed
- Time Period
- 18th century,Modern
- Property Information
- Trinity House
- Object Number
- Access Status