VOLTA, BUNSEN & DANNIELL; 19TH CENTURY

Volta was a Jesuit and professor of physics in Padova who together withGalvani, a physician from Bologna conducted a remarkable series of experiments which showed the properties of electricity. In brief Galvani showed that when two disimilar metals were in contact with each other and the outer ends touched a nerve in a frog, a violent contraction occurred! Galvani felt that this was due to electricity generated by the animal itself, but Volta showed in a series of experiments that this was due to the contact of the two dissimilar metals. This occurred in 1786, and the discovery of the Voltaic pile, of which this is a demonstration model (probably made for a university) made possible the generation of different voltages when a soaked piece of paper or silk was placed between the discs; adding to the number of discs increased the voltage. The same concept was also used for powering radar in aircraft in the Second World War where huge voltage and compactness was required. Lastly, the Voltaic 'crown of cups' which generates huge voltages was recently used in hydrogen fusion experiments. The voltaic pile was used in the late eighteenth and nineteenth centuries but most electric clocks were impulsed by an earth battery, which was cheaper.