Referee's report by Archibald Geikie, on a paper 'Niagara falls as a chronometer of geological time' by J W Spencer Not recommended for publication in the 'Philosophical Transactions of the Royal Society'. Much of the information has already been published. The new information is mostly opinion, with little fact to test this upon. The calculations are given, but do not provide any new principles. The summary published in the Proceedings will suffice. Subject: Geology [Published in the 'Proceedings of the Royal Society of London', 1894] 6 June 1894