In spring 1871 Alexander became Royal Surveyor-General, and Edward Payson Church replaced him as president of Punahou. As the head of the Kingdom's Survey Department, Alexander led a trigonometrical mapping project that eventually produced a map of the islands which the Kingdom showcased at the 1876 World's Fair in Philadelphia. Alexander with Luther Aholo represented the Kingdom of Hawaii at the International Meridian Conference, held in Washington, DC, in October 1884. This conference resulted in the selection of the Greenwich Meridian as an international standard for zero degrees longitude.