Faraday to Peter Henry Berthon   8 February 1860

Royal Institution | 8 Feby 1860

Sir

In reply to your letter of the 1st instant¹, I have drawn up a set of enquiries which, in my opinion, it would be necessary to make, and have answered, before any proposal to introduce the lime light into a lighthouse could be considered. These I beg to submit to the consideration of the Deputy Master² and Elder brethren. As far as I am concerned, such preliminary enquiries and answers would be required in every like case.

I am Sir | Your faithful humble Servant | M. Faraday

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

Enquiries &c

1 The Trinity House cannot undertake to consider a mere proposition, or an imperfect arrangement; but only such subjects as are presented to them in a practical state.

2 The T.H. cannot undertake to work out, or perfect, the application of a proposition, though it may feel justified in undertaking to test a perfected arrangement, upon good reasons and data being submitted to it

3 In order to enable the T.H. to judge whether a proposition made to them by parties, not practically experienced in the service of lighthouses, is well founded and has been thoroughly considered, it is desirable that certain questions should be answered; not from expectation only, but upon principle and from experience:- These, in the present case, may be founded upon the requisites for a first order fixed light; and may be as follows.

[1]³ 4 What is the quantity of light proposed to be supplied; expressed, either in relation to a central Fresnel lamp of four wicks, or to an ordinary Argand burner such as is used in a reflector?

[2] 5. The number of jets required to ignite the lime?

[3] 6. The quantity of oxygen required for 12 hours?

[4] 7. The current price of the oxygen? i.e. the cost of material, wages, repairs, and any other current expence.

[5] 8. The manner of storing the oxygen?

[6] 9. The nature of the gas fuel? – the quantity required in 12 hours?

[7] 10. How is the gas fuel to be obtained? How is it to be stored?

[8] 11. What is its current price for 12 hours; including materials, wages, repairs, and other current expences?

[9] 12. What is the shape and size of the lime or focal light? How often will it require renewal?- How, or where, is it to be obtained? – and what will be its current cost?

[10] 13. What degree of steadiness will the light possess? Is it now as steady as a well burning lamp, or is it unsteady, like a lamp in draughts? – or does it sink and rise at intervals?

[11] 14. Will the attention of the keeper be, of necessity, perpetual? – If not, for what intervals has the light been left, as yet, without falling off in character?

[12] 15. What is the vertical height, and horizontal width of the most intense part of the luminous object? – and what the height of the part which may be called, generally, intensely luminous?

[13] 16. What number of persons would it be necessary to employ upon the spot, in relation to the lighthouse? – and what would be their occupations?

[14] 17. What buildings or outhouses for retorts, gazometers, &c, and what habitations besides, those now belonging to a first order lighthouse, would be required?

[15] 18. Are the means of obtaining the light considered as applicable, only in favourable situations, or in all ordinary situations? In the latter case, let the reply have relation to such a lighthouse as that at Dungeness or Flamboro’ Head.

[16] 19. Are there any exceptional cases where the light could not be applied with advantage;- as the Needles – Eddystone – Bishops – Longships – Plymouth breakwater – Casquets – Longstone – Bell rock – Skerryvore – Stack – Smalls – Tuskar – and others? If so, are they supposed to be few or numerous?

[17] 20. Will the service of the lime light make it dependent upon the neighbourhood of a town? – or if not so dependent, what kind of annual supplies, - or supplies at considerable intervals, will probably be required?

[18] 21. What will be the probable outfit of the apparatus with the building necessary for it and for the accommodation of the extra staff required?

[19] 22. What will be the nature of the necessary repairs?

[20] 23. What will be the whole current expence of the application of the lime light? (Including Royalty &c)

The T.H. cannot authorize any chance of interference with the certainty of lighthouse action by the introduction of any uncertain or unproved arrangements tending to disturb the actual service of the light. It therefore requires full proof of the fitness of any proposed arrangement, before considering its introduction into a lighthouse[.]

Any failure in such preliminary proof, or any serious departure in the results, from the answers given to the questions 4. 5. 6. 7. 9. 10. 11. 12. 13. 14. 16. 17. 18. 20. 23, which can be as well obtained out of a lighthouse as in it, will be considered as shewing that the proposed application has not been sufficiently matured;- and if not removed by further investigation and proof, will lead to the conclusion, that the method is not applicable to the service of lighthouses⁴.

M. Faraday

8 Feby 1860

Endorsement: No. 661 | Universal Lime Lt. | Professor Faraday submittd set of preliminary enquiries which will be also suitable to similar cases.- | 8. Feb: 1860. | 15/2/60. | (Enter in Scientific Reports) Folio 346 | Board 14 Feb 1860 communicated the points of Enquiry as suggested by Mr Faraday to Mr Baxter⁵.