Faraday to Jacob Herbert   20 October 1855

Royal Institution | 20 Octr. 1855

Sir

In reference to your letter of the 11th instant¹, I beg to state that I proceeded to the Glass works at Birmingham on Tuesday last² for the purpose of examining Messrs. Chances Catadioptric apparatus[.] It was well fitted up so as to give me every opportunity of looking at it. I found the colour of the glass very good indeed as good as the pannels approved of on former occasions. Some of the ribs were striated in parts but it is impossible to avoid this altogether without enormous expence & as far as my memory serves the apparatus is not in that respect beneath those I have seen from or in France. The fitting & work of the glass & frames is good. I took a pannel down & examined it by the suns rays and found the focal distances of the several parts perfectly adjusted for the lamp distance[.]

At night when the lamp was burning I examined it from steps & a stage placed at the distance of 57 yards so as to command it at different levels and by revolving the apparatus on all sides & found the action as it ought to be. Then retreating to the distance of 225 yards, I examined it again & still had every reason to be satisfied with the apparatus as being equal in all points to the French Apparatus. I therefore beg to express my approval of it³[.]

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

Jacob Herbert Esqr | &c &c &c