were some of the engineering masterpieces of their time, notably those at Bell Rock, Skerryvore, and Muckle Flugga. Between 1876 and 2005 the NLB also maintained foghorns at a number of locations. The last (at Skerryvore) was sounded for the last time on 4 October 2005. Operations The board is based at its Georgian headquarters building in George Street in the centre of Edinburgh, from where it remotely monitors its network. Technical operations are carried out from a base in Oban, Argyll and Bute, where there are maintenance workshops and facilities for the construction of buoys and beacons. The NLB's vessels are also based here. The Oban depot has been recently modernised. Under the terms of the Scotland Act 1998, the NLB is not a devolved body and thus remains directly accountable to the UK Secretary of State for Transport. In practice, there is close co-operation with both the Scottish Government and the Isle of Man Government. The NLB is funded by pooled light dues administered by the UK's Department for Transport, and distributed to the NLB, Trinity House, and the Commissioners of Irish Lights. Assets As of 31 March 2019, the NLB operates the following: Navigational devices Statutory 206 lighthouses, sub-divided as: 65 with a range of over 15 nautical miles 141 with a range of under 15 nautical miles 170 buoys 25 unlit beacons 4 DGPS stations (and monitoring an additional 2 stations) 29 radar beacons, sub-divided as: 22 on lighthouses 9 on buoys 47 Automatic identification system units, sub-divided as 26 on lighthouses (and monitoring an additional 1 unit) 20 on buoys 3 Virtual AIS unit Contract 2 lighthouses (and 2 in Norwegian waters) 117 buoys 3 radar beacons (and 2 in Norwegian waters) Local Authority 1117 light stations 762 buoy stations Vessels The NLB operates two lighthouse tenders, known by the prefix Northern Lighthouse Vessel, or NLV. has been in service since 2000 and was delivered on 31 March 2007 to the Oban depot. This is the tenth Pharos, replacing the ninth Pharos which was sold in September 2006 for use as a Fishery Protection vessel for South Georgia and the South Sandwich Islands. The commissioners Most of the commissioners have always been ex officio appointments. The original commissioners appointed in 1786 were the Scottish law agents of the Crown, the sheriffs of Scotland's coastal counties, and the provosts and lord provosts of Scottish cities and