chunk: As found by a new research expedition, the circumference of Gallia was 2320Â km. The mass of the comet was calculated by Rosette. He determined it at 209,346 billion tonnes. For the calculation he used spring scales and forty 5-franc silver coins, the weight of which on earth equaled exactly to one kilogram. However, the owner of the scales, Isaac Hakkabut, had rigged the instrument, so the results had to be cut by a quarter.