This Week in History: June 26-July 2, 2017 for human events ever resemble those of preceding times.” Machiavelli June 26 1721 – Dr. Zabdiel Boylston of Massachusetts gives the first untested smallpox inoculation in America to his own son. 1797 – Charles Newbold patents the first cast-iron plow. He can’t sell it to farmers because they fear the effects of iron on soil. 1870 – The Christian holiday of Christmas is declared a federal holiday in the U.S. 1900 – U.S. Army physician Dr. Walter Reed begins research that, in 1901, leads to the discovery of how to beat Yellow Fever. His experiments with other doctors in Cuba prove that mosquitoes transmit Yellow Fever.