At first, as in the case of ancient glaciers, through sheer want of capacity, the mind refuses to take in revealed facts. But by degrees the steady contemplation of these facts so strengthens and expands the intellectual powers, that where truth once could not find an entrance it eventually finds a home. [Footnote: The formation, connection, successive subsidence, and final disappearance of the glacial lakes of Lochaber were illustrated in the discourse here reported by the model just described, constructed under the supervision of my assistant, Mr. John Cottrell. Glen Gluoy with its lake and road and the cataract over its col; Glen Roy and its three roads with their respective cataracts at the head of Glen Spey, Glen Glaster, and Glen Spean, were all represented. The successive shiftings of the barriers, which were formed of plate glass, brought each successive lake and its corresponding road into view, while the entire removal of the barriers caused the streams to flow down the glens of the model as they flow down the real glens of to-day.] A map of the district, with the parallel roads shown in red, is annexed. LITERATURE OF THE SUBJECT. THOMAS PENNANT.--A Tour in Scotland. Vol. iii. 1776, p. 394. JOHN MACCULLOCH.--On the Parallel Roads of Glen Roy. Geol. Soc. Trans. vol. iv. 1817, p. 314. THOMAS LAUDER DICK (afterwards SIR THOMAS DICK-LAUDER, Bart.)--On the Parallel Roads of Lochaber. Edin. Roy. Soc. Trans. 1818, vol. ix. p. 1. CHARLES DARWIN.--Observations on the Parallel Roads of Glen Roy, and of the other parts of Lochaber in Scotland, with an attempt to prove that they are of marine origin. Phil. Trans. 1839, vol. cxxix. p. 39. SIR CHARLES LYELL.--Elements of Geology. Second edition, 1841. Louis AGASSIZ.--The Glacial Theory and its Recent Progress--Parallel Terraces. Edin. New Phil. Journal, 1842, vol. xxxiii. p. 236. DAVID MILNE (afterwards DAVID MILNE-HOME).--On the Parallel Roads of Lochaber; with Remarks on the Change of Relative Levels of Sea and Land in Scotland, and on the Detrital Deposits in that Country. Edin. Roy. Soc. Trans. 1847, vol. xvi. p. 395. ROBERT CHAMBERS.--Ancient Sea Margins. Edinburgh, 1848. H. D. ROGERS.--On the Parallel Roads of Glen Roy. Royal Inst. Proceedings, 1861, vol. iii. p. 341. THOMAS F. JAMIESON.--On the Parallel Roads of Glen Roy, and their Place in the History of the Glacial Period. Quart. Journal Geol. Soc. 1863, vol. xix. p. 235. SIR CHARLES LYELL.--Antiquity of Man. 1863, p. 253. REV. R. B. WATSON.--On the Marine Origin of the Parallel Roads of Glen Roy. Quart. Journ. Geol. Soc. 1865, vol. xxii. p. 9. SIR JOHN LUBBOCK.--On the Parallel Roads of Glen Roy. Quart. Journ. Geol. Soc. 1867, vol. xxiv. p. 83. CHARLES BABBAGE.--Observations on the Parallel Roads of Glen Roy. Quart. Journ. Geol. Soc. 1868, vol. xxiv. p. 273. JAMES NICOL.--On the Origin of the Parallel Roads of Glen Roy. 1869. Geol. Soc. Journal, vol. xxv. p. 282.