James Timmins Chance to Faraday   29 November 1860

Hamstead | Birmingham, | 29 Nov: 1860

My dear Sir,

I trust that you arrived comfortably at London last night: I was very sorry to hear of your detention at the Spon Lane Station.

I feel quite sure that no conclusions should be deduced from the images on the white paper or from the whole set together of the upper, or lower ribs; any more than from the image from the whole panel.

The only safe way is that which you & I have followed vizt:- to decide the focus of each rib separately.

They cannot be taken together, except at such a distance as to see nearly the same part of the flame simultaneously from all the belts or ribs;- that is, many miles away.

I will send you, in a day or two, coloured drawings of the respective images of the flame, received on the white paper from the different ribs & the middle belt; so as to indicate the relative positions of those images, and to shew the way in which they would lie one above another when the light comes from the whole panel.

I will take the 20mm focus, & the 28mm focus, as two separate cases; and for each case there shall be marked the level line for each rib, to assist the eye.

Possibly before you come to any conclusion for lights generally, you might like to view at a good distance the effect upon the eye through the whole panel of different positions of the flame, from 28mm down to 18mm above the burner.

This can be readily done, & wd seem to be quite worth the extra trouble for so important a matter.

For the ‘Smalls’ Light, however, I fancy that your present data, as derived from Tuesday’s¹ experiments will enable you to decide upon the positions of the belt & ribs in reference to the burner.

Most truly yours | James T. Chance

Prof: Faraday