1915 Each summer adults try to concoct fresh ideas on how to beat the heat. But these children arrived at a simple yet practical solution: getting doused with a watering can. In fact, this image looks like a precursor to the modern Ice Bucket Challenge, in which celebrities drench themselves with ice water to raise funds to combat the neurodegenerative condition ALS, aka Lou Gehrig’s disease. The photo here was taken years before air conditioning became common in homes, offices, and autos. Willis Carrier invented the electrical air conditioning unit and put it into practice in 1902 in order to regulate the temperature and humidity at a printing plant in Brooklyn, N.Y. However, the first time air conditioning was used in a widespread sense for human comfort was right here in Detroit. In 1924, three Carrier centrifugal chillers were installed at the J.L. Hudson department store, delighting shoppers (and employees). Once the public was wrapped in that refreshingly cool embrace, there was no looking back. But it would be decades before the luxury of air conditioning would be considered a ubiquitous social necessity whenever people went indoors. Still, a good soaking of cool water on a scorching day seems so much more fun.