Dunsink Observatory

The Dunsink Observatory is an astronomical observatory established in 1785 in the townland of Dunsink near the city of Dublin, Ireland.

Its most famous director was William Rowan Hamilton, who, amongst other things, discovered quaternions, the first non-commutative algebra, while strolling from the observatory into the centre of the city with some friends and his wife. He is also renowned for his Hamiltonian formulation of dynamics. In the late 20th century, the city encroached ever more on the observatory, which compromised the seeing. The telescope, then no longer state of the art, was used mainly for public 'open nights'.