Jacob's Well is a perennial karstic spring in the Texas Hill Country flowing from the bed of Cypress Creek, located northwest of Wimberley, Texas. The twelve foot (four meter) diameter mouth of the spring serves as a popular swimming spot for the local land owners whose properties adjoin Cypress Creek. From the opening in the creek bed, Jacob's Well cave descends vertically for about thirty feet (ten meters), then continues downward at an angle through a series of silted chambers separated by narrow restrictions, finally reaching a depth of one hundred and twenty feet (forty meters). Until the modern era, the Trinity Aquifer-fed natural artesian spring gushed water from the mouth of the cave, with a measured flow in 1924 of one hundred and seventy gallons per second (six hundred and forty liters per second) discharging six feet (two meters) into the air. The spring is the greatest source of water recharging the Edwards Aquifer.

“Wells Cathedral is a Church of England cathedral in Wells, Somerset, England. Built between 1175 and 1490, Wells Cathedral has been described as “the most poetic of the English Cathedrals”. The Wells clock, an astronomical clock, is located in the north transept. The surviving mechanism, dated to between 1386 and 1392, was replaced in the 19th century, and was eventually moved to the Science Museum in London, where it continues to operate. It is the second-oldest surviving clock in England”. – Wikipedia

Photo: The clock face of world's oldest continually-working mechanical clock is seen as it is hand wound for the very last time on August 21, 2010 in Wells, England. (Photo by Matt Cardy/Getty Images)

A leopard trapped in a well looks up to forest officials on the premises of the Kamakhya temple in Gauhati, India, Thursday, April 4, 2013. According to locals, the leopard fell into the well while scouring for food. (Photo by Anupam Nath/AP Photo)

A two-horse team street cleaner, with sprayer, squeegee, and roller at rear. New York, between ca. 1910 and ca. 1915. (Photo by NYC Municipal Archives)

General view of the screens in Hyde Park to showing the Royal Wedding on April 29, 2011 in London, England. The marriage of Prince William, the second in line to the British throne, to Catherine Middleton is being held in London today. The Archbishop of Canterbury conducted the service which was attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding and street parties are being held throughout the UK. (Photo by Tom Dulat/Getty Images)

Pro-government fighters stand next to a tank destroyed during recent fighting in Yemen's southwestern city of Taiz March 14, 2016. (Photo by Anees Mahyoub/Reuters)

Documentary photographer William E. Crawford was one of the first Western photographers to gain access to North Vietnam after the war ended. He has photographed the capital, Hanoi, at regular intervals since 1985, concentrating on the colonial and indigenous architecture, urban details, landscapes and intimate portraits of people in their home settings, street scenes and the city’s surrounding countryside. Here: 54 Hàng Ga (Chicken Street), 1994. (Photo by William E. Crawford from the book “Hanoi Streets 1985-2015: In the Years of Forgetting”)