Henry Enfield Roscoe to Faraday   18 March 1861

Owens College, | Manchester, | March 18. 1861

(Kirch[h]off’s directions for arranging Steinheils apparatus¹)

(Translation by H.E.R.)

Observation-Telescope is to be [word obscured]² out until a very distant object appears plainly. It is then [word obscured] screwed into the Ring A, [word obscured] the screws B & C have been [word obscured] loosened as to render this possible.

The second telescope is to be screwed [word obscured] the ring belonging to it, & the [word obscured] of both telescopes brought nearly into one straight line, & then the slit drawn out until it can be plainly seen through the telescope.

The Screws B & C (one of which is a screw for pressing, & the other a screw from drawing) are then made tight so that the Telescope does not shake about & that the middle of the slit, (ie. the dividing line between the open & covered parts of the slit) appears nearly in the centre of the field of view.

The prism is next pushed into the angle-brasses F, after loosening the screw (D) & spring (E) - & then the spring E tightened.

The observation telescope is now turned until the spectrum appears.

The piece of black cloth is thrown over the prism & over the ends of the telescopes nearest the prism.

The lamps are to be placed on the circles, the arms of the supports brought over the straight lines, & each support moved in the direction of its arm until the bead is brought into the outer mantle of the flame.