Plant-maps for the Netherlands 1:3.000.000. Part I. Compiled by „The Institute for the Investigation of the Vegetation in the Netherlands” (I.V.O.N.)

This publication is a continuation of „Plantenkaartjes voor Nederland”, published by Dr. J. W. C. GOETHART and Dr. W. J. JONG MANS in the years 1902—1908. For both publications the same methods, differing in two respects from those usually adopted elsewhere, have been employed. As in the first place it is utterly impossible to show on a very small-scale map, the exact spot where a certain species of plant is to be found, this mock-accuracy has been avoided. Only that part of the topographical map is indicated, which contains the finding-place. With this end in view, each of the 64 sheets of the survey-map of the Netherlands is covered by a net of 48 rectangles, each side being approximately one hour’s walk long (exactly 4180 X 5000 metres). These rectangles are called „hour-squares”, each being subdivided into 16 „quarter-hoursquares” of 1045 X 1250 metres. The „hour-square”, in which any special finding-place of a plant occurs, is clearly shown on a photo-lithographically reduced map with the „hour-square” division. As the scale of the reduced map is left large enough, even the „quarter-hour-square” in question can be clearly distinguished within its „hour-square”.