American Heritage® Dictionary of the English Language, Fourth Edition
- n. A telescope equipped to measure small angular distances between celestial bodies.
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. Each half of the objective forms its own image of a star, this image moving with the half-objective which forms it. Thus, the image of one star, formed by one half of the objective, can be brought into coincidence with the image of another, formed by the other half, and by means of the micrometer the distance apart of the half-lenses, and consequently the angular distance of the two stars, can be very accurately measured, while the position-angle is determined by the direction of the line of separation of the semi lenses. This instrument is much employed in investigations into the parallax of the fixed stars, as well as for other purposes. As its name implies, it was originally devised for measuring the diameter of the sun.
- 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.
GNU Webster's 1913
- n. (Astron.) 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.
- 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
- helio-, from Ancient Greek Ἥλιος (Hēlios), from ἥλιος (hēlios, "sun") + meter, from French mètre, from Ancient Greek μέτρον (metron, "measure"). (Wiktionary)
“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.”
Looking for tweets for heliometer.