While flipping through William Herschel's 1801 Philosophical Transactions paper "Observations tending to investigate the Nature of the Sun in order to find the Cause of Symptoms of its Variable Emission of Light and Heat", I thought it was a good early-ish paper on sunspots. I was surprised to find a lengthy entry on the applied nature of his findings, and that on the variable nature of sunspots and agricultural yield as determined by wheat prices found in Adam Smith's Wealth of Nations. Honestly I was fully unaware of Herschel's involvement with sunspots and seasonal growth and price fluctuations, but there it was. And he does find a correlation, albeit a very cautious one where he says the subject deserves more study and more data.
He writes: "it seems probable that some temporary scarcity or defect of vegetation has taken place, when the sun has been without those appearances which we surmise to be the symptoms of a copious emission of light and heat..."
This must make Herschel--already a celebrity astronomer for his discovery of the first planet discovered since ancient times, Uranus, among many other things--one of the earliest (if not the first) astronomer to experimentally entertain the effects of solar disturbances on the Earth. And this on sunspots years before Schwabe established the periodicity of sunspots (1846) or the electromagnetic connection with sunspots (that would come only with G.E. Hale in 1908). Herschel (who left/fled Germany to reside in England) was a man of interesting sight: he discovered Uranus, identified new moons of Saturn, established that the previously-nebulous nebulae were collections of vast numbers of distant and faint clouds, drew a spectacular image of the Milky Way galaxy as an outside observer looking in, that there was a light from the sun that was beyond the visible spectrum, and also discovered in the micro-world found that coral were animals rather than plants.The business of trying to see if there were any correlations between solar activity and plant production on Earth was novel, and interesting. [The original paper is available for purchase through our blog bookstore, here.]