In 1910 it was converted to run automatically on acetylene;[5] the gas was manufactured in an adjacent producer plant and controlled by a sun valve.

A new fixed third order Fresnel lens was installed in the lantern[6] and a red sector was added to the main light to indicate lines of approach that were hazardous for shipping.

It served to warn shipping of the Megstone, an isolated rocky island lying (in line with the two lights) just under a mile away to the north-west.

This light was also designed by Daniel Alexander and was similar to the other two in appearance and layout but taller;[11] it too was equipped with a revolving set of lamps and reflectors.

[12] It likewise replaced an earlier light built by Captain Blackett in 1778 (on nearby Staple Island, but subsequently relocated to Brownsman).