His expertise was Mediterranean archaeology and primitive time-reckoning. With the use of the planetarium in Pittsburgh in 1940, he was able to work out the precise date that the ancient Egyptians used as their starting date of their calendar, June 18, 3,251 B.C.E.. He ruined plans for
Columbia University in 1956 who had been planning the 2,000th anniversary of the
Ides of March when he notified them that it would only be the 1,999th anniversary as "'March 15, 1 B.C. to March 15 1 A.D. equals one year', he pointed out that there was no zero year." The University of Pennsylvania Museum, led by Johnson, excavated
Minturnae and collected over "100 pieces of sculpture" from 1931-1933. The majority of the sculptures were left in Italy, where "many were misplaced or lost in the course of World War II." Discovered scratched into a plaster wall of a private home in
Dura-Europos Johnson found a sketch of the zodiac and words in Greek. He managed to read that this was the
horoscope of an infant child provided by an astrologer based on the date of birth of the baby. When Johnson returned to Yale, he took his work to the astronomy department, which used the sketches of the planets and determined that the child had been born July 3, 176 C.E. at about 10pm. Johnson believed that because of looting, "[T]he greatest archeological discovers ... will be made underwater". Although many shipwrecks held common cargoes of
amphora jugs, occasionally a ship "had a cargo of some of the finest marble and bronze statuary of the ancient world, bound for the villas and public buildings of Rome. ... They await us in almost mint condition." (sitting without kitten) ==Works==