1856 Tidal Chart of the British Isles

This is Johnston's Tidal Chart of the British Isles. The map was included in the 2nd edition of Johnston's Physical Atlas of Natural Phenomena, published out of Edinburgh by William Blackwood & Sons in 1856. The chart depicts ports, coastal towns and cities throughout the British Isles, and includes a few along the coasts of Norway, Germany, the Netherlands and France. Depths of the water are annotated and indicated by varying shades of grey. The chart also denotes the hour of high water in Greenwich time, at both new and full moon, and the rise and fall of spring tides.  At the time of publication, Alexander Keith Johnston's Physical Atlas of Natural Phenomena was amongst the most comprehensive geographic works focusing on natural science. Johnston described the motivations and focus of his work in the preface as follows; The object originally contemplated in this work was to present, in a graphic form, a concise yet comprehensive view of the Physical Geography of the Globe, embra