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.

Students from Langata primary school run past riot police as they protest against a perimeter wall illegally erected by a private developer around their school playground in Kenya's capital Nairobi January 19, 2015. Riot police used teargas to disperse students at a school in Nairobi as the children protested against the potential loss of their playground. The playground was fenced off in December, during the school holidays, by a prominent developer who also claims ownership of the land. The title to the contested site is said to be in the name of Airport View Housing Limited, according to local media, with plans to use the space to build a parking lot for a hotel. (Photo by Thomas Mukoya/Reuters)

These chilling images prove there is no sign of life at this abandoned tuberculosis treatment hospital. Johnny Joo, 24, captured the eerie shots of the desolate TB ward, in Perrysburg, New York. Where equipment lies gathering rust and walls are left crumbling. The photojournalist, from Cleveland, Ohio, stumbled upon the facility, which shut its doors in 1995, before shooting what remains of the historic site. Johnny said the facility, named after Buffalo Mayor James Nobel Adam, remains something of an unknown quantity as it is surrounded by more than 500 acres of forest land. (Photo by Johnny Joo/Caters News)

Pictures from Tasmania’s central plateau, shot by wilderness photographer Dan Broun, show the extraordinary damage wrought by more than a week of bushfires following lightning strikes in Australia’s southernmost state on January 13. 2016. The world heritage area was home to a range of unique alpine flora including pencil pines, king billy pines and cushion plants, some more than 1,000 years old. Now more than 10,000ha of land has been incinerated, and ecologist say that, unlike eucalyptus trees, the ancient flora will not recover. (Photo by Dan Broun)

Ayesha Farooq, 26, Pakistan's only female war-ready fighter pilot watches an airforce jet about to take off at Mushaf base in Sargodha, north Pakistan June 7, 2013. Farooq, from Punjab province's historic city of Bahawalpur, is one of 19 women who have become pilots in the Pakistan Air Force over the last decade – there are five other female fighter pilots, but they have yet to take the final tests to qualify for combat. A growing number of women have joined Pakistan's defence forces in recent years as attitudes towards women change. (Photo by Zohra Bensemra/Reuters)

A Nepalese devotee offers ritual prayer at the Bank of Bagmati River of Pashupatinath Temple during Rishi Panchami Festival celebrations at Kathmandu, Nepal on Sunday, August 23, 2020. Rishi Panchami festival is celebrated as the last day of three-day long Teej Festival. The Teej festival is celebrated by Hindu women in Nepal as well as in some parts of India. (Photo by Narayan Maharjan/NurPhoto via Getty Images)

Afghan boys ride on donkey cart transporting plastic bottles for recycling, on the outskirts of Kabul, Afghanistan, on 16 September 2020. Nearly 19 years after the fall of the Taliban regime and the United States invasion, the Afghan government and insurgents on 12 September, began peace negotiations in Doha. (Photo by Hedayatullah Amid/EPA/EFE)

Number 10. BELL H-13 SIOUX was a two-bladed, single engine, light helicopter built by Bell Helicopter. Westland Aircraft manufactured the Sioux under license for the British military as the Sioux AH.1 and HT. In 1947, the United States Air Force ordered the improved Bell Model 47A. Most were designated YR-13 and three winterized versions were designated YR-13A. The United States Army first ordered Bell 47s in 1948 under the designation H-13. These would later receive the name Sioux. The Bell-built H-13 B is seen airborne in this April 29, 1951 photo. The helicopter is equipped with a 173 horsepower engine, cruises at 85 miles per hour, climbs 900 feet in a minute and has a service ceiling of 11,500 feet. (Photo by AP Photo)