Faraday to Jacob Herbert   11 October 1854

Report &c

Royal Institution | 11 October 1854

My dear Sir

Since Friday¹ last I have been to Haisboro², according to your instructions³, & visited both the lights. I found nothing wrong in the lanthorns, nor any complaints from the Keepers respecting them. There is no sweating on the glass, for it is always perfectly dry internally, & the ventilation perfect. You are aware that the ventilating tubes are applied to the lamps, & the testimony of the keepers, is, that there was condensation on the glass before their application, but that there is none now. On a long cold night, sometimes between 3 & 4 pints of water are condensed in the collecting ball at the upper lighthouse; but none at the lower, where it is all carried out at the cowl by the ventilation.

The keepers, who have in part to live in the towers, complain of great dampness there; and there are sufficient proofs that the complaints are well founded. This part of the subject I leave to the far superior judgement of Messrs. Walker & Cooper⁴. But I may remark that the source of dampness appears to me to be from above, and is probably of the following nature. The towers are 60 years old or more and are of brick; they are painted externally & partly internally, but fissures & cracks occur in this covering, & there are also fissures between the large window frames which are numerous & the surrounding brick work. When a driving rain beats against & runs down the tower, it is in part drawn into these fissures; & sometimes the keepers have to put pails to catch what is driven through at the windows, though they are not made to open as casements. Such water as thus soaks into the brick work cannot evaporate outwards, because of the paint; & has to be removed entirely by internal evaporation; & as the rooms are closed, & fires are not kept up in the fire places as in old times (as the keeper of his own knowledge tells me was the case) so they are now very damp.

The division of the towers into rooms cuts off, as it were, the open connexion between the tower & the lanthorn, and it supplies as I think good illustrations of the value of that principle, which I have recently commended to the Trinity House⁵. The lanthorns are good, but the towers are, as to dampness, bad; & we have each exhibiting its state when separated from the other⁶.

I am My dear Sir | Your Very faithful Servant | M. Faraday

Jacob Herbert Esq | Secretary &c &c &c