The Siloam (Shiloach) inscription or Silwan inscription (in reference to Jerusalem neighborhood called Silwan) is a passage of inscribed text originally found in the Hezekiah tunnel (which feeds water from the Gihon Spring to the Pool of Siloam in East Jerusalem). The tunnel was discovered in 1838 by Edward Robinson (so Amihai Mazar, Archaeology of the Land of the Bible  484). The inscription records the construction of the tunnel in the 8th century BCE. It is among the oldest extant records of its kind written in Hebrew using the Paleo-Hebrew alphabet. Traditionally identified as a "commemorative inscription", it has also been classified as a votive offering inscription.
History of the discovery
Despite Hezekiah's tunnel being examined extensively during the 19th century by such eminent archaeologists as Dr. Edward Robinson, Sir Charles Wilson, and Sir Charles Warren, they all missed discovering the inscription, probably due to the accumulated mineral deposits making it barely noticeable.
According to Easton's Bible Dictionary (1897), a youth, while wading up Hezekiah's tunnel from the Siloam Pool end, discovered the inscription cut in the rock on the eastern side, about 19 feet into the tunnel.
The Siloam inscription was surreptitiously cut from the wall of the tunnel in 1891 and broken into fragments; these were, however, recovered by the efforts of the British Consul at Jerusalem, and have been placed in Istanbul Archaeology Museum. Although housed in Turkey, Jerusalem Mayor Uri Lupolianski made the request on July 12th, 2007 in a meeting with Turkey's ambassador to Israel, Namik Tan to return the tablet to Jerusalem as a "goodwill gesture" between allies. Turkey has rejected such request, stating that the Siloam inscription was Imperial Ottoman Property, and thus is the cultural property of the Turkish Republic. However, President Abdullah Gul, stated that as a good will gesture from Turkey, they will display the inscription in Jerusalem for a short period .
In 1899, another tunnel, also leading from the Gihon Spring to the Siloam Pool area, but by a more direct route, was found. This latter tunnel is now known as the Middle Bronze Age channel, on account of its estimated age; Reich determined that it was constructed around 1800 BC (in the Middle Bronze Age). It is essentially a 20 feet deep ditch in the ground, which after construction was covered over by large rock slabs (which were then hidden in the foliage). It is narrower, but can still be walked by a human for most of its length. In addition to the (3ft high) exit near the Siloam pool, the channel has several small outlets that watered the gardens facing the Kidron Valley.
The ancient city of Jerusalem, being on a mountain, is naturally defensible from almost all sides, but suffers from the drawback that its major source of fresh water, the Gihon spring, is on the side of the cliff overlooking the Kidron valley. This presents a major military weakness as the city walls, if high enough to be defensible, must necessarily leave the Gihon spring outside, thus leaving the city without a fresh water supply in case of siege.
The Bible records that King Hezekiah (whom Albright dates to 715-687 BC), fearful that the Assyrians would lay siege to the city, blocked the spring's water outside the city and diverted it through a channel into the Pool of Siloam.
2 Kgs 20:20 (NRSV), “The rest of the deeds of Hezekiah, all his power, how he made the pool and the conduit and brought water into the city, are they not written in the Book of the Annals of the Kings of Judah?”
2 Chr 32:3-4 (NRSV), “he planned with his officers and his warriors to stop the flow of the springs that were outside the city; and they helped him. 4 A great many people were gathered, and they stopped all the springs and the wadi that flowed through the land, saying, “Why should the Assyrian kings come and find water in abundance?””
Unreadable at first due to the deposits, Professor A.H. Sayce was the first to make a tentative reading, and later the text was cleaned with an acid solution making the reading more authoritative. The inscription contains 6 lines, of which the first is damaged. The words are separated by dots. Only the word zada on the third line is of doubtful translation - perhaps a crack or a weak part.
The passage reads:
- ... the tunnel ... and this is the story of the tunnel while ...
- the axes were against each other and while three cubits were left to cut? ... the voice of a man ...
- called to his counterpart, (for) there was ZADA in the rock, on the right ... and on the day of the
- tunnel (being finished) the stonecutters struck each man towards his counterpart, ax against ax and flowed
- water from the source to the pool for 1200 cubits. and 100?
- cubits was the height over the head of the stonecutters ...
The inscription hence records the construction of the tunnel; according to the text the work began at both ends simultaneously and proceeded until the stonecutters met in the middle. However, this idealised account does not quite reflect the reality of the tunnel; where the two sides meet is an abrupt right angled join, and the centres do not line up. It has been theorised by 21st century archaeologists that Hezekiah’s engineers depended on acoustic sounding to guide the tunnelers and this is supported by the explicit use of this technique as described in the Siloam Inscription. The frequently ignored final sentence of this inscription provides further evidence: “And the height of the rock above the heads of the laborers was 100 cubits.” This indicates that the engineers were well aware of the distance to the surface above the tunnel at various points in its progression. 
- ↑ R.I. Altman, "Some Notes on Inscriptional Genres and the Siloam Tunnel Inscription", Antiguo Oriente 5 (2007) 35-88.
- ↑ Images of the Middle Bronze Age channel
- ↑ 
- A clearer photo of the inscription
- Siloam Inscription - Transcription and Vocalization
- A ligature in the inscription
- Jewish Encyclopedia: Siloam Inscription, includes image
- Catholic Encyclopedia: Siloear:نقش سلوانhu:Silóah-felirat