A late 18th century/ early 19th century glass sand timer. The glass bulb is encased by beech spindles with turned top and bottom and takes approx 30 minutes to run through. These were often used by the Royal Navy up until 1839 to count in half hours and for marines as a dependable measure of time whilst at sea. It has also been documented that these half hour timers were used in the church pulpit for measuring the parsons sermon to ensure it did not overrun what a good idea.!!!!! Also these antique timers were used for measuring labourers break times!! It measures approx 16.5cm in height and 9.5cm in diameter.