Terrestrial telescope, 1752.
© Science Museum / Science & Society Picture Library
When in Bordeaux, France, in 1752, Dr Stephen Demainbray (1710-1782), a science lecturer of the time, bought this telescope from a maker named Costa. It appears to be an ordinary instrument of the period, but in fact it has six lenses which was unusal. A terrestrial telescope is used for observations on land and at sea, the image seen being the right way up.