Neptune was the first planet to be discovered by using mathematics. After the discovery of Uranus in 1781, astronomers noticed that the planet was being pulled slightly out of its normal orbit. John Couch Adams of Britain and Urbain Jean Joseph Leverrier of France, used mathematics to predict that the gravity from another planet beyond Uranus was affecting the orbit of Uranus. Johann Gottfried Galle searched for the predicted planet and observed Neptune for the first time in 1846.
The infection spread from India to Afghanistan in 1839 There were sporadic outbreaks over the next 6 years before it reappeared in India & the Middle East in 1845. It spread to Russia, where it is estimated that it caused at least a million deaths. And by 1848 it had hit Europe. In 1854, more than 23,000 died in Britain alone.