Robert Welbank to Faraday   22 June 1856¹

My Dear Mr Farraday

Our short parley of last night would give you but a faint idea of what I wished to convey to you upon the subject of a light onboard of a vessel moored in a narrow Channel for the purpose of Lighting only a small portion of the circle instead of the whole circumference-

In consequence of the many distressing accidents to Sailing vessels through the carelessness or want of a good look out onboard of Steamers - I have proposed at the Trinity House to light a new Channell for the express use of Steamers by Night and to relieve all other Channels in the Neighbourhood from their intrusion by Night.

A light vessel being under the influence of the Wind & tide frequently changing her position & swinging round by either power and never or seldom quite steady - It has occurred to me that the Magnetic Needle might be made available to keep open at all times as much of the circle and direction of the Ray of light as might be required and obscuring all not required - as for example - If I want a Channell to be lighted East & West - North & South should be obscured to prevent the Spark or focal ray being sent beyond the narrow ridge up and bounding the Channell[.]

In a Ship the magnetic pole is always the same point - I therefore think if the Needle can be made to traverse upon the Centre point laden at the North & South ends with a shade of any obscuring property - however slight the focal Ray in those directions will be sufficiently deadened to prevent accidents by being mistaken for any other Light Vessel or Light House near to it[.]

Suppose therefore a Lamp to be placed in the centre of a vessel shewing its focal Ray all round the compass -. A pin passing up the Centre of the Lamp within the burners and glass tubes above to a proper height to prevent being melted by the heat and then the Magnetic Needle made to embrace the whole one points North the other South and sufficiently poised with the obscuring weights at the extremes of the Needle - I think my object would be attained -

Have the kindness to give this idea your serious thought & oblige the Father of the Corporation of Trinity House[.]

Robert Welbank

Trinity House June 22nd 1856