Faraday to Peter Henry Berthon   19 April 1859

Royal Institution | 19. April 1859

Dear Sir

I examined the Apparatus for the North Foreland lighthouse yesterday¹ and found it very excellent. The glass is very good and its colour though of the French blue-green tint, is very small, especially in the thinner & principal parts of the apparatus. The pieces are well worked & well associated together i.e optically:- for as regards the fittings of the central ribs into the sides of the metal frame these sides, as was observed by Captn Close & others, thicker than they need be, having regard to due strength; & they cause obstruction of light.

The two large back reflectors are imperfect in form & throw the light very irregularly back towards the lamp flame:- This is perhaps inevitable considering the size of the reflectors & the mode of their manufacture still such light will be sent seaward, & will aid, irregularly, in strengthening the visible light at sea[.]

The very imperfect action of the lower reflecting ribs, because of the obstruction offered by the size of the burner, when the flame is not more than 2½ or 3½ inches high; presses itself into notice in these examinations. If the flame could with a good combusting be made higher & not so much compressed in width in the upper part it would be a great advantage to lighthouses placed on a high level; for all the extra light which would then reach these lower ribs would be thrown on to the sea between the horizon & the shore; very important parts to be strengthened in light in hazy weather²[.]

I am | Dear Sir | Your Very Obedient faithful Servant | M. Faraday

P.H. Berthon Esqr | &c &c &c | Trinity House