Faraday to Robert Faraday   10 January 1843

Royal Institution, | Jan. 10, 1843

My dear Brother,

If I understand the questions in your letter aright they arise upon the supposition of lighting the hall of Devonshire house in three different ways, i.e. either by eighteen of your ventilated gas burners - or by eighteen equal ordinary gas burners - or by oil lamps in the same situation equal in light to the same 18 gas burners - and the questions are which mode will communicate the least heat to the air and which will least affect the air in giving to it impurity.

I believe that your lamps¹ will give the least heat to the air for the following reasons - as compared to the ordinary gas lamp they must give less - because being so near the wall and the pipes soon enclosed the burnt air passing off must go away hot - and so much heat at all events is removed - whereas the ordinary gas lamp gives all it[s] heat to the air of the place - As compared to oil lamps giving equal light it is no doubt true that the combustion of the oil for that purpose does not evolve so much heat as gas - on the other hand an oil lamp gives all its heat to the air and your lamp does not - and it is my opinion from what I saw of the hall and the proposed place of the lamps that the quantity of heat carried off by the flues would reduce the heating effect of your lamps below that of oil lamps - and perhaps considerably.

As to the sweetness of the air of course neither of the other modes can compare with yours.

Yoursaffectionately, | M. Faraday