Passage: In 1900, near the site of the ancient Byzantine city of Theodosia, thirteen large piles of stones were discovered by Zibold who was a forester and engineer in charge of this area. Each stone pile covered just over 900 square metres (9,700 sq ft) and was about 10 metres (33 ft) tall. The finds were associated with the remains of 75-millimetre diameter (3.0 in) terracotta pipes that apparently led to wells and fountains in the city. Zibold concluded that the stacks of stone were condensers that supplied Theodosia with water; and calculated that each air well produced more than 55,400 litres (12,200 imp gal; 14,600 US gal) each day.To verify his hypothesis Zibold constructed a stone-pile condenser at an altitude of 288 metres (945 ft) on mount Tepe-Oba near the ancient site of Theodosia. Zibold's condenser was surrounded by a wall 1 metre (3 ft 3 in) high, 20 metres (66 ft) wide, around a bowl-shaped collection area with drainage. He used sea stones 10–40 centimetres (3.9–15.7 in) in diameter piled 6 metres (20 ft) high in a truncated cone that was 8 metres (26 ft) in diameter across the top. The shape of the stone pile allowed a good air flow with only minimal thermal contact between the stones.Zibold's condenser began to operate in 1912 with a maximum daily production that was later estimated to have been 360 litres (79 imp gal; 95 US gal) – Zibold made no public record of his results at the time. The base developed leaks that forced the experiment to end in 1915 and the site was partially dismantled before being abandoned. (The site was rediscovered in 1993 and cleaned up.) Zibold's condenser was approximately the same size as the ancient stone piles that had been found, and although the yield was very much less than the yield Zibold had calculated for the original structures, the experiment was an inspiration for later developers.

Question: What year was the experiment put to a halt?
1915