Search the Dictionary

A telescope arranged and used to determine errors of collimation, both vertical and horizontal. Nichol.

A telescope of low power, having a large field of view, used for finding comets.

an unfavorable wind. -- Cross wires, fine wires made to traverse the field of view in a telescope, and moved by a screw with a graduated head, used for delicate astronomical observations; spider lines. Fixed cross wires are also used in microscopes, etc.

The act of defining; determination of the limits; as, the telescope accurate in definition.

Having the quality of unloosing or separating. Clarke. Dialytic telescope, an achromatic telescope in which the colored dispersion produced by a single object lens of crown glass is corrected by a smaller concave lens, or combination of lenses, of high dispersive power, placed at a distance in the narrower part of the…

used in instruments to cut off marginal portions of a beam of light, as at the focus of a telescope.

eans of the refraction of light; refractive; as, the dioptric system; a dioptric glass or telescope. "Dioptrical principles." Nichol. Dioptric curve (Geom.), a Cartesian oval. See under Cartesian.

isk; appearing as a point and not expanded into a disk, as the image of a faint star in a telescope.

star (Astron.), two stars so near to each other as to be seen separate only by means of a telescope. Such stars may be only optically near to each other, or may be physically connected so that they revolve round their common center of gravity, and in the latter case are called also binary stars. -- Double time (Mil.).…

A level having a short telescope (hence its name) rigidly fixed to a table capable only of rotatory movement in a horizontal plane. The telescope is usually an inverting one. It is sometimes called the Troughton level, from the name of the inventor, and a variety improved by one Gavatt is known as the Gavatt level.…

An instrument for determining the magnifying power of telescopes, consisting usually of a doubleimage micrometer applied to the eye end of a telescope for measuring accurately the diameter of the image of the object glass there formed; which measurement, compared with the actual diameter of the glass, gives the magnify…

An instrument consisting of a telescope so mounted as to have two axes of motion at right angles to each other, one of them parallel to the axis of the earth, and each carrying a graduated circle, the one for measuring declination, and the other right ascension, or the hour angle, so that the telescope may be directed,…

An attachment to a microscope, telescope, or other optical instrument, for making the image erect instead of inverted.

Eyepiece of a telescope, microscope, etc.

The lens, or combination of lenses, at the eye end of a telescope or other optical instrument, through which the image formed by the mirror or object glass is viewed. Collimating eyepiece. See under Collimate. -- Negative, or Huyghenian, eyepiece, an eyepiece consisting of two plano-convex lenses with their curved sur…

One who, or that which, finds; specifically (Astron.), a small telescope of low power and large field of view, attached to a larger telescope, for the purpose of finding an object more readily.

e highest rank; in the first division; of the best quality; first-rate; as, a first-class telescope. First- class car or First-class railway carriage, any passenger car of the highest regular class, and intended for passengers who pay the highest regular rate; -- distinguished from a second-class car.…

r, or more exactly, in the case of a lens, from its optical center. --Focal distance of a telescope, the distance of the image of an object from the object glass.

(In the field of a telescope) In the direction from which stars are apparently moving (in consequence of the erth's rotation); as, a small star, north following or south following. In the direction toward which stars appear to move is called preceding.

posed of innumerable stars, so distant and blended as to be distinguishable only with the telescope. The term has recently been used for remote clusters of stars. Nichol.