 By 1856, he had made sufficient progress for Leopold II, Grand Duke of Tuscany to take an interest in his work, and the following year he travelled to Paris where he was assisted by the engineer Paul-Gustave Froment, to whom he had been recommended by Léon Foucault, to construct the first pantelegraph.In 1858, Caselli's improved version was demonstrated by French physicist Alexandre-Edmond Becquerel at the French Academy of Sciences in Paris.On 10 May 1860 Napoleon III visited Froment's workshop to observe a demonstration of the device, and was so enthused by the device that he secured access for Caselli to the telegraph lines he needed to further his work, from Froment's workshops to the Paris Observatory.