E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
i.e. the Greek IHΣ, meaning IHΣoυ (Jesus), the long e (H) being mistaken for a capital H, and the dash perverted into a cross. The letters being thus obtained, St. Bernardine of Siena, in 1347, hit upon the Latin anagram, Jesus Hominum Salvator. In Greek, Ioυε Hεεo Σ. In German, Jesus Heiland Seligmacher. In English, Jesus Heavenly Saviour.
I.H.S. A notarica of Japheth, Ham, Seth, the three sons of Noah, by whom the world was peopled after the Flood.