September 18 marks the birthday of the discovery and naming of Yellowstone Park’s Old Faithful, Fox News reports.

The geyser, which spews out water 90 feet (ca. 27 m) to 125 feet (ca. 38 m) in the air was first discovered on September 18, 1870, by Nathanial Langford, a member of the Washburn-Doane-Langford expedition.

In his journal, Langford added that they named it Old Faithful because its eruptions were so regular:

It spouted at regular intervals nine times during our stay, the columns of boiling water being thrown from ninety to one hundred and twenty-five feet at each discharge, which lasted from fifteen to twenty minutes. We gave it the name of “Old Faithful.”

— Nathaniel P. Langford, 1871^[6]

And though it’s a popular tourist attraction today, there was a time when people used it to launder their clothes which Henry Winser described in a manual that he wrote about the geyser in 1883:

“Old Faithful is sometimes degraded by being made a laundry. Garments placed in the crater during quiescence are ejected thoroughly washed when the eruption takes place. Gen. Sheridan‘s men, in 1882, found that linen and cotton fabrics were uninjured by the action of the water, but woolen clothes were torn to shreds.“

Depending on how much water was released in the previous eruption, the geyser takes between 44 minutes to 125 minutes to build up pressure for the next one and typically has about 20 eruptions a day.

READ: On this day in history, September 18, 1870, Old Faithful geyser in Wyoming is documented and named