I took out the little collimating screws first, then I drew out the tube, and in that I found a brass plate screwed on the diaphragm which contained the lines.
I was at first a little puzzled to know which screws held this diaphragm in its place, and, as I was very anxious not to unscrew the wrong ones, I took time to consider and found I need turn only two.

Then out slipped the little plate with its three wires where five should have been, two having been broken.

As I did not know how to manage a spider's web, I took the hairs from my own head, taking care to pick out white ones because I have no black ones to spare.

I put in the two, after first stretching them over pasteboard, by sticking them with sealing-wax dissolved in alcohol into the little grooved lines which I found.

When I had, with great labor, adjusted these, as I thought, firmly, I perceived that some of the wax was on the hairs and would make them yet coarser, and they were already too coarse; so I washed my little camel's-hair brush which I had been using, and began to wash them with clear alcohol.
Almost at once I washed out another wire and soon another and another.