 Complete the following phrase:  On 17 August, 26 August, 21 October, and 10 November 1852 Welsh made, for the Kew committee, four ascents from Vauxhall, with the assistance of Charles Green, in his balloon the Great or Royal Nassau. The purpose was to make meteorological observations, and a detailed description was published in Philosophical Transactions in 1853. In March and May 1854 he made for the committee an investigation on the pumping of marine barometers, an artefact of the rolling motion of ships. In 1855 Welsh went to the 