 Tyndall's recommendation was that the siren should provide the standard fog signal at major landfall stations, with reeds judged suitable at some sites; by 1884 sirens were in use at 22 coastal stations and on 16 lightships.Tyndall presented wider conclusions on the acoustic effects of different atmospheric conditions in a paper delivered to the Royal Society the following year.In 1876 Tyndall was again engaged to make a comparative study at South Foreland, this time of two different types of electric generator