Where are these on the St. Louis U. High campus?
Try these for more information about this symbol
from WikepediaSeal of the Society of Jesus. The "IHS" comprises the first three Greek letters of "IHΣOYΣ", "Jesus" in Greek, later reinterpreted as "Iesus Homini Salvator" ("Jesus, Saviour of Mankind") or "Iesum Habemus Socium" ("We have Jesus as Companion")
from the Internet Encyclopedia of Religon
Jesuit symbol in San Ignacio
ISH on Jesuit gravestones in Shanghai China