As a key factor in ensuring that European sailing vessels reached North American shores, understanding the trade winds was becoming a matter of great importance at the time.
Hadley was intrigued by the fact that winds which should by all rights have blown straight north had a pronounced westerly flow, and it was this mystery he set out to solve.
He had an unremarkable childhood, and was eclipsed in his early years by his older brother John Hadley (1682–1744), the inventor of the octant (a precursor to the sextant).
He was called to the bar on 1 July 1709, but remained more interested in mechanical and physical studies than in legal work[1] For 7 years, succeeding William Derham, he was in charge of interpreting the meteorological diaries sent to the Royal Society from observers around the world, mainly in Britain and Scandinavia.
[2] Later, in the second half of the 19th century, Hadley's theory was itself shown to be deficient in that it was based on an assumption that when air mass travels from one latitude to another its linear momentum is conserved.