Barometer Simultaneous barometric readings from across a network of weather stations allow maps of air pressure to be produced, which were the first form of the modern weather map when created in the 19th century. Isobars, lines of equal pressure, when drawn on such a map, give a contour map showing areas of high and low pressure. Localized high atmospheric pressure acts as a barrier to approaching weather systems, diverting their course. Atmospheric lift caused by low-level wind convergence into the surface brings clouds and sometimes precipitation. The larger the change in pressure, especially if more than 3.5 hPa (0.1 inHg),
Tube map no complete maps of the network, just for the individual companies' routes. These maps were not typically schematic and were simply the line overlaid on a regular city map. There was no integration of the companies' services, nor was there any co-operation in advertising. In 1907, "The Evening News" commissioned a pocket map titled The Evening News London "Tube Map". This map was the first to show all of the lines with equal weight given to each line. In addition, it was the first to use a different colour for each line. Another early combined map was published in 1908