William Derham FRS (1657 – 1735)was an English clergyman, natural theologian and natural philosopher. He produced the earliest, reasonably accurate estimate of the speed of sound. Derham was elected Fellow of the Royal Society in 1703.
The best known of his works are Physico-Theology; Astro-Theology; and Christo-Theology,. All three are teleological arguments for the being and attributes of God, and were used by William Paley nearly a century later.
However, these books also include quantities of original scientific observations. Physico-Theology contains his recognition of natural variation within species and that he knew that Didelphis virginialis (the Virginia opossum) was the only marsupial in North America. It also includes one of the earliest theoretical descriptions of a marine chronometer, accompanied by a discussion of the use of vacuum seals to reduce inaccuracies in the operation of timepieces.
Similarly, Astro-Theology includes several newly identified nebulae (this was the name used at the time for all extended astronomical objects: some of his nebulae are what we would now call star clusters).
In 1709 Derham published a more accurate measure of the speed of sound, at 1,072 Parisian feet per second. Derham used a telescope from the tower of the church of St Laurence, Upminster to observe the flash of a distant shotgun being fired, and then measured the time until he heard the gunshot with a half second pendulum. Measurements were made of gunshots from a number of local landmarks, including North Ockendon church. The distance was known by triangulation, and thus the speed that the sound had travelled was calculated.
Reference:
Thomas Dereham to Hans Sloane, 1731-04-28, Sloane MS 4051, ff. 227-228, British Library, London.
William Derham, Wikipedia, [https://en.wikipedia.org/wiki/William_Derham, accessed 22/08/17]
Dates: to
Occupation: Unknown
Relationship to Sloane: Virtual International Authority File: