Wind measurements. Scientists recording wind speed measurements at the Royal Observatory, Greenwich, London. The weather vane on top of the tower indicates the wind direction. The apparatus below is connected to the vane, and pens have been attached to draw lines on paper to indicate the maximum wind speeds (gusts). As well as being an astronomical observatory, this site was also used to carry out meteorological investigations, including measurements of magnetic fields, wind speed, and other geographical and geological phenomena. Engraving from 1880.