The Longitudes Examin'd

At the TLS, Pat Rogers considers a hoax pamphlet that has taken in countless scholars of the eighteenth-century attempt to develop a method for ascertaining longitude. One of the genuine schemes Rogers also discusses

involved the use of strategically placed ships which would fire off a number of shells programmed to explode at a set time. Even during foggy weather the explosions would be audible, and, just in time for the project, a reasonably accurate estimate (very slightly on the high side) had been made for the speed of sound, using gunshot reports. The findings came from the Revd William Derham, himself a man well versed in clockmaking, and they were published by the Royal Society in 1709. The committee had already looked at the Whiston–Ditton proposal, and the pair optimistically drafted an advertisement to launch a heavy press campaign, declaring that their method had been “so far approved by this present Parliament, that they have passed an Act, ordering a reward of 20000£. for such a Discovery”. In the event, the flying bombs turned out to be unworkable and did not get into contention for the prize. If Whiston had restrained himself on the subject of the early Church and the need for a reformed liturgy, he might have sat in judgement on his own idea. Nothing daunted, he arranged a display to prove his theory in July 1715: this involved letting off rockets at intervals across an area of thirty-six square miles centred on Hampstead.