Some Account of the Strata and Volcanic Appearances... 1790.

Fig. 1. View of the Glen near Ardlun Head in Mull.
Fig. 2. View of the insulated Rock at the termination of the Glen.
Fig. 3. A view of the great Fissure, the Cave and the suspended Stones, in the Island of Mull. The fissure ranges N. and S., is about ten feet wide and forty yards deep: the sides and the suspended stones are granite.

From: Some account of the Strata and Volcanic Appearances in the North of Ireland and Western Isles of Scotland. In two letters from Abraham Mills Esq. to John Lloyd, Esq. F.R.S. Read January 21, 1790. Published in Phil. Trans. Vol LXXX. 

The Giant's Causeway

BGS image ID: P006483

Giant's Causeway. Looking SE. Columnar jointing in tholeiitic basalt. The columns are usually from five to seven sided with ball and socket cross-joints. 
Old photograph number: NI00708

BGS image ID: P225384

Giant's Causeway. Looking SE. Columnar tholeiitic basalt, showing ball and socket cross-jointing. The cross-joints are upward and downward facing in apparently random pattern.
Old photograph number:  NI00706

BGS image ID: P225386

Giant's Causeway. Looking N. The Middle Causeway. Columnar tholeiitic lava.
Old photograph number:  NI00710

Bob McIntosh