"[Lot of 2] Distribution of Heat over the Globe [and] Humboldt's System of Isothermal Lines…", Johnston, W. & A.K.
Subject: Thematic Maps
Period: 1856 (circa)
Publication: Physical Atlas
Color: Printed Color
24 x 20 inches
61 x 50.8 cm
Pair of interesting thematic maps. First sheet includes six world maps; each with isothermal and isabnormal diagrams for different times of the year. Second is a large world map on Mercator's projection illustrating Humboldt's system of Isothermal Lines, which was developed in 1817 and provided the means of comparing the climatic conditions of various countries. Size varies slightly.
Keith Johnson worked in conjunction with German Heinrich Berghaus to produce the Physical Atlas, which resulted in the first truly comprehensive thematic atlas. The maps are very early examples of printed color, the development of which made a huge impact on cartography in general and specifically the graphic portrayal of geographical data on thematic maps.
References: Robinson, pp. 64-67.