Letter from Samuel Haughton, Trinity College, Dublin to Edward Sabine Refers to Mr [John Bobanau Nickerlieu] Hennessey, and discusses the use of a tub outside to collect water and give a ‘water surface continuous’ with the water in the gauge. Haughton acknowledges the difficulties Hennessey mentions but admits he does not know how to alleviate them. Haughton suggests using a ‘large surface of water’. 10 December 1866