In the 1840s, he began to experiment with disease cures and mechanics. His wife Penelope died of yellow fever on September 5, 1844. Frequent epidemics had swept through the nation, and the disease had a high rate of fatalities during the 19th century. Borden began experimenting with finding a cure to the disease via refrigeration. No one understood how it was transmitted. He also experimented with an amphibious vehicle that he called a "terraqueous machine." This was a sail-powered wagon designed to travel over land and sea, but designed more specifically for the western prairies. He abandoned the invention after a test run resulted in ejecting its riders into the Gulf of Mexico.