George Henry Bachhoffner to Faraday   24 August 1858

Royal Colosseum, | Regents Park & Albany Street, | London Augst. 24th. 1858

Dear Sir.

I beg to send you the following statistics of the cost of 2 lime lights for a period extending from Jany. 1st. to March 31st. being 77 working days, total time of burning each day upon the average being 4 hours. I feel them to be unsatisfactory for any practical purpose without the photometric value that I am having a lime light attached to my Bunsens photometer¹ and should this investigation afford you any additional information I shall have much pleasure either in sending you the result or, should you like to go through them yourself I shall me most happy to see you any day you may appoint between 5 and 7.

I am, Dear Sir, | Yours truly | Geo H. Bachhoffner

M. Faraday Esqr | D.C.L. F.R.S. &c

The total cost of generating oxygen and Hydrogen for 2 lime lights for 3 months, 77 working days each light burning 4 hours daily.

Cost of each light burning 77 days x 4 hours = 308 hours²