This chart shows the results of the first British state-sponsored expedition with a purely scientific purpose. Because the earths magnetic field is not uniform and, as a result, the mariners compass points either side of north to a variable degree depending on the ships position. To make navigation safer, Halley made an extensive series of comparisons between compass readings and determinations of…

This is another variation on the supposed raft being built by the French for the invasion of Britain in early 1798 (for example, see PAH7433). Unlike other prints produced during this wave of paranoia in London, which represent the vessel as an excessively fantastic contraption more appropriate to the tales of Baron Mnchhausen, this print pares it down to a severe geometric symmetry to assert its …