Faraday to Peter Henry Berthon   11 May 1860

Royal Institution | 11 May 1860

Sir

The additional answers obtained from the Universal lime light company are to the point¹, except, that to question 18. The question is “What will be the probable outfit of the apparatus, with the buildings necessary for it and for the accom[m]odation of the extra staff required?” You will see that the answer makes no reference to the buildings, gazometers, retorts, and extra staff required.

The answers generally are such, as, in my opinion, to justify the Trinity House in permitting a trial on a full scale, of the applicability of the lime light to lighthouse purposes: provided it can be done so as to give full practical information on all matters, and without injury or interruption to the service. Such a trial should be sustained night after night for a given time, that the following, amongst other, points may be tested, namely;- the character and power of the light (that being at the time under general observation) - its constancy - its liability to accidents - its capability of replacement by the ordinary central lamp - its call on the keepers attention - the requisite number of persons for the service - the manufacture and storing of the gases - the quantity of gases consumed - the cost in full of the gases - the cost of wages - the cost of outfit and whole expence.

It is not for me to judge where such a trial could be best made: but wherever made, I think it should depend upon its own appliances as much as a lighthouse removed from the neighbourhood of a town and placed on a distant coast. I think too, it should be subject to the continual observation of external night watchers; and if they be mariners, or such as are concerned in lighthouse action, so much the better. The South Foreland upper light is an admirable station for observation; but perhaps cannot be permitted to be used on this occasion. The Purfleet lighthouse might serve, but would not be under good observation, or observation in all directions. I think a fixed light is the proper condition in which the light should be observed. If Purfleet, however, or any such situation, were chosen, it would not be necessary to have six jets on the lime, nor could they all be watched, by persons external to the lighthouse: perhaps three would do; only, this would not make the full call on the nightly supply of gas, and so far would leave the trial imperfect[.]

Will you allow me to say that not having the answers to my questions, nor copies of them, I find myself frequently at a loss, when I desire to refer to them²[.]

I have the honor to be | Sir | Your Very humble Servant | M. Faraday

P.H. Berthon | &c &c &c

Endorsement: No. 2309 | Universal Lime Lt | Professor Faraday reporting upon additional answers. | 11 May 1860. Entd in book of Scientific Reports (Folio 355) | Board 15 May 1860 | Wardens & Lt Comm to arrange for Trial at So. Foreland High Light | PHB