It is said that he watched the operations in comfort while seated before the eyepiece of a periscope carried up through the roof.

I thought it nice ladylike work to manage such slight threads and turn such delicate screws; but fine as are the hairs of one's head, I shall seek something finer, for I can see how clumsy they will appear when I get on the eyepiece and magnify their imperfections.

For methods of observation, I rely generally on the simple eye-observation, possibly relieved of some of its uncertainty by the use of my colour-correcting eyepiece.

I may state here that by availing myself of a theory of eyepieces which I published long since in the Cambridge Transactions, I have been able to effect a considerable improvement in the telescopes furnished to the Admiralty.

May 21 Eyepieces of Telescopes.

[microscope components] objective lens, eyepiece, barrel, platform, focusing knob; slide, slide glass, cover glass, counting chamber; illuminator, light source, polarizer, [component parts of telescopes] reticle, cross-hairs.

It should have a good prism eyepiece with an angle tube attached so it would not be necessary to break one's neck in reading high altitudes.

He edged as far as he could between the wooden seat and the eyepiece of the instrument, and turned his body round so that it was chiefly his feet that were exposed.

And then he saw the eyepiece of the telescope with a lot of red smears on it.

In addition to all this labour, he perfected a twelve-inch speculum of vast magnifying power before the spring of 1784; and many hours were spent at the turning-bench, as not a night clear enough for observing ever passed without the devising of improvements in the mounting and motion of the various instruments then in use, or the test and trial of newly-constructed "eyepieces," most of which were executed by Herschel's own hands.