1896, Harry Forbes Witherby, Light from the Land of the Sphinx, page 157:
The collimator consists of a convex lens at the end of a tube, with a vertical slit, or a pair of cross-wires, in the focus; the telescope is a common telescope with a positive eye-piece, and a pair of cross-wires in the focus of the eyepiece.
1936, Ganesh Bhaskar Deodhar, Introduction to Optics, page 152:
This is so adjusted that the image of the cross-wires C formed by reflection at the surface of the glass plate coincides with the cross-wires themselves without parallax.
1957, Richard Samuel Longhurst, Geometrical and Physical Optics, page 78:
As the telescope is swung round, the slit image for each wavelength is brought into coincidence with the cross-wires.
2010, Isaac Roberts, Photographs of Stars, Star-Clusters and Nebulae, page 27:
A small telescope, having a magnifying power of about seventy diameters, with cross-wires fixed in its eyepiece, is firmly fixed with adjusting screws to the back of the cell, and pointed through the hole in the cell and mirror towards the focus of the mirror, where the photo-plate is fixed.
