from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A telescope equipped to measure small angular distances between celestial bodies.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An astronomical instrument, based on a telescope, for measuring the diameter of the sun; now used to measure the angular distance between stars and other celestial bodies.
from the GNU version of the Collaborative International Dictionary of English
- n. An instrument devised originally for measuring the diameter of the sun; now employed for delicate measurements of the distance and relative direction of two stars too far apart to be easily measured in the field of view of an ordinary telescope.
from The Century Dictionary and Cyclopedia
- n. An astronomical instrument, consisting of a telescope having its objective sawed across in a plane passing through the optical axis, and each part arranged to move by sliding past the other, its exact position being shown by a micrometerscrew.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an instrument used to measure the angular separation of two stars that are too far apart to be included in the field of view of an ordinary telescope
A heliometer is the most accurate astronomical instrument for relative measurements of position, as a transit circle is the most accurate for absolute determinations.
But there is one instrument of great value, the heliometer, which is not used at Greenwich.
 The heliometer is a telescope with its object-glass cut in half along a diameter.
Joseph Fraunhofer perfected the refracting telescope, as Herschel had perfected the reflector, and invented a wonderfully accurate "heliometer," or sun-measurer.
Thus, from 606 measures of Venus on the sun, taken with a new kind of heliometer at
The heliometer, there can be no doubt, is the special instrument for the purpose, and it was, moreover, that employed by
Its aperture is of only six inches, while that of the Oxford heliometer is of seven and a half; but the perfection of the arrangements adapting it to the twofold function of equatorial and micrometer stamps it as a model not easy to be surpassed.
Dr. Elkin's work with the Repsold heliometer at Yale College.
Munich, who constructed a magnificent heliometer for the Observatory at
He invented the necessary machines, constructed a spherometer, and developed the moving and measuring devices used in astronomical telescopes, such as the screw micrometer and the heliometer.