James Timmins Chance to Faraday   6 December 1860

Hamstead | Birmingham | 6 Dec: 1860

My dear Sir,

Many thanks for the copy, now returned, of your report¹.

page 2. line 6 from top.

“much higher & varying points”-

perhaps it would be better to this effect:- “focal points in the axis varying from about 18mm to 30mm above the burner”;- because the words “much higher” apply to only a few of the lower ribs.

p.3 line 7 from the top.

What do you think of adding that “even with a very high flame the focal points of the middle belt & upper ribs cannot be raised higher than 23mm or 24mm above the burner without sending the brightest light to the sky.” Without some such limitation, it might be inferred from your description that for high flames the focus might be allowed to ascend to 28mm or more.

I do not think that the foci of the lower ribs would have to be changed for any increased height of flame.

p.1. line 11 from bottom

the word “to” should be “as”

I feel no anxiety as to 20mm for the “Smalls” Light:- for if at any time it is wished to lower the burner, either 1mm or more, no harm whatever wd be done to the upper or lower reflectors, by the small quantity involved.

I say nothing about the notions of the Royal Commrs. - Profr. Airy - &c &c in regard to the lens experiments, because you are sure to learn their opinion from themselves when you see them.

Very truly yours | James T. Chance

P.S. I enclose Chance Bros & Co.’s account for the 2nd set of Exps².