Eilean Musdile is an islet, and lighthouse

Lighthouse

A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

 to the south west of Lismore

Lismore, Scotland

Lismore is a partially Gaelic speaking island in the Inner Hebrides of Scotland. This fertile, low-lying island was once a major centre of Celtic Christianity, with a monastery founded by Saint Moluag and the seat of the Bishop of Argyll.-Geography:...

 in the Inner Hebrides

Inner Hebrides

The Inner Hebrides is an archipelago off the west coast of Scotland, to the south east of the Outer Hebrides. Together these two island chains form the Hebrides, which enjoy a mild oceanic climate. There are 36 inhabited islands and a further 43 uninhabited Inner Hebrides with an area greater than...

.

The island lies in the entrance to Loch Linnhe

Loch Linnhe

Loch Linnhe is a sea loch on the west coast of Scotland....

, separated from Lismore by a sound ¼ miles across. It is a low-lying rock, ten acres (4 ha) in size, with some grass on it. CalMac

Caledonian MacBrayne

Caledonian MacBrayne is the major operator of passenger and vehicle ferries, and ferry services, between the mainland of Scotland and 22 of the major islands on Scotland's west coast...

 ferries pass close to the island on their way from Oban

Oban

Oban Oban Oban ( is a resort town within the Argyll and Bute council area of Scotland. It has a total resident population of 8,120. Despite its small size, it is the largest town between Helensburgh and Fort William and during the tourist season the town can be crowded by up to 25,000 people. Oban...

 to Mull

Isle of Mull

The Isle of Mull or simply Mull is the second largest island of the Inner Hebrides, off the west coast of Scotland in the council area of Argyll and Bute....

.

The lighthouse was built by Robert Stevenson

Robert Stevenson (civil engineer)

Robert Stevenson FRSE MInstCE FSAS MWS FGS FRAS FSA was a Scottish civil engineer and famed designer and builder of lighthouses.One of his finest achievements was the construction of the Bell Rock Lighthouse.-Early life:...

 in 1833 at a cost of £4260 and initially showed a fixed white light. In 1910 most of the Northern Lighhouse Board's lights were changed to dioptric or Fresnel lens

Fresnel lens

A Fresnel lens is a type of lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses.The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design...

es but Lismore and Fidra

Fidra

Fidra is an uninhabited island in the Firth of Forth, north-west of North Berwick, on the east coast of Scotland.-Geography:...

, in the Firth of Forth

Firth of Forth

The Firth of Forth is the estuary or firth of Scotland's River Forth, where it flows into the North Sea, between Fife to the north, and West Lothian, the City of Edinburgh and East Lothian to the south...

, were left as the only remaining purely catoptric lights

Catoptrics

Catoptrics deals with the phenomena of reflected light and image-forming optical systems using mirrors. From the Greek κατοπτρικός ....

 in the service.

A Standing Stone once stood on the highest point of the island . The 9 feet (2.7 m) monolith appears to have recorded the midwinter sunset and is thought to have been removed during construction of the lighthouse.

The skerry of Lady's Rock

Lady's Rock

Lady's Rock is a skerry to the south west of Lismore in the Inner Hebrides. It is submerged at high tide and carries a naviagtion beacon. Eilean Musdile is to the north east, next to Lismore.-History:...

lies a short distance to the south west.