Daylight Savings Time - "Saving" or "Savings"?

According to the Wikipedia, the first use of DST occurred during WW1, initiated by Germany and Austria-Hungary. The term used was "sommerzeit", which appears to translate into English as "Summer Clock". Perhaps this is the origin of the term used by the Israeli gov't?

The relevant U.S. Code on the subject that dates to 1966 describes the act to be taken (moving clocks ahead/back) and the dates on which the adjustments are to take place, but doesn't use the term "daylight saving(s) time" at all.

An executive order from President Richard Nixon in 1973 temporarily ordering year-round DST in the United States, described it as "daylight saving time" [singular, not plural]. (Coincidentally, enacted as a result of the Arab oil embargo due to America's support for Israel in the 1973 war.)

I really have no idea where the plural in "daylight savings time" came from, but oddly, it's something that I've heard people use since childhood in America.