| 单词 | heliometer |
| 例句 | When the heliometer-part of Lord Lindsay’s heliometer was acquired by Gill in 1879, he changed the manner of imparting the motion in question. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z Physicists were sometimes jocularly greeted among astronomers as "ribbon men," and no one even dreamed that their researches were one day to advance to equal recognition with results derived from micrometer, meridian circle, and heliometer. Astronomy: The Science of the Heavenly Bodies 2012-03-17T02:01:02.630Z They are obtained from late improved measures of the velocity of light, and from measures by the heliometer. Scientific American Supplement, No. 648, June 2, 1888. 2011-12-26T03:00:15.410Z A heliometer is the most accurate astronomical instrument for relative measurements of position, as a transit circle is the most accurate for absolute determinations. Pioneers of Science These two traditional methods were supplemented in 1874 by the camera and the heliometer. A Popular History of Astronomy During the Nineteenth Century Fourth Edition Still more recently the Repsolds have completed a new heliometer for Yale College, New Haven, United States. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z His instrument was the heliometer, originally designed for measuring the sun's diameter; but as modified for parallax work it is the most accurate of all angle-measuring instruments that the astronomers employ. Astronomy: The Science of the Heavenly Bodies 2012-03-17T02:01:02.630Z The Messrs. Repsold have established, and for the present seem likely to maintain, a practical monopoly in the construction of heliometers. Scientific American Supplement, No. 623, December 10, 1887 The center of this hall is occupied by a massive pier of stone, 10 feet square, passing from the basement into the dome above, and intended for the support of the great heliometer. The Uses of Astronomy An Oration Delivered at Albany on the 28th of July, 1856 Bessel had no sooner made himself acquainted with the exquisite defining powers of the Königsberg heliometer, than he resolved to employ them in an attack upon the now secular problem of star-distances. A Popular History of Astronomy During the Nineteenth Century Fourth Edition In Bessel’s heliometer this would amount to a difference of 15⁄1000th of an inch when an angle of 1� is measured. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z The inner corona had first been recorded photographically on a daguerreotype plate during the eclipse of 1851, but the lens belonged to a heliometer, and was of course uncorrected for the photographic rays. Astronomy: The Science of the Heavenly Bodies 2012-03-17T02:01:02.630Z Among these are an anemometer slowly revolving in the light air, maximum and minimum bulbs in the shade, on the ground and beneath it, a most ingenious sun dial, and a heliometer. A Journal of a Tour in the Congo Free State The transit instrument, the meridian circle, the mural circle, the heliometer, and the sextant, belong to this class. The Uses of Astronomy An Oration Delivered at Albany on the 28th of July, 1856 A detailed examination convinced the Astronomer-Royal of its superior accuracy to Bessel's result with the heliometer. A Popular History of Astronomy During the Nineteenth Century Fourth Edition Modern heliometers made with cylindrical slides measure angles over 2�, the images remaining as sharp and perfect as when the smallest angles are measured. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z But there is one instrument of great value, the heliometer, which is not used at Greenwich. History of Astronomy Struve’s second suggestion has been adopted in nearly all succeeding heliometers. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z Again, in an ocular heliometer by Steinheil double image is similarly produced by a divided prism of total reflection placed in parallel rays. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z They frequently recur; they need no elaborate preparation; a single astronomer armed with a heliometer can do all the requisite work. A Popular History of Astronomy During the Nineteenth Century Fourth Edition An arrangement, afterwards described, has been fitted in modern heliometers for placing the screen in front of either segment by a handle at the eye-end. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z In 1877 Sir David Gill used Lord Crawford’s heliometer at the Island of Ascension to measure the parallax of Mars in opposition, and found the sun’s distance 93,080,000 miles. History of Astronomy It is probable that the Bonn heliometer was in course of construction before these suggestions of Struve were published or discussed, since its construction resembles that of the K�nigsberg and Pulkowa instruments. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z But, as it came from the hands of the makers in 1849, the Oxford heliometer was incomparably the most powerful and perfect instrument in the world for the highest order of micrometric research. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z A series of observations can be easily and more accurately accomplished with the Cape heliometer in half an hour; with the Oxford heliometer it would occupy 2 hours, and with the 4 in. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z This instrument suggested to Struve the above-mentioned idea of employing a similar motion for the heliometer. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z He considered that, while the superiority of the heliometer had been proved, the results would be still better with the points of light shown by minor planets rather than with the disc of Mars. History of Astronomy Gill introduced a powerful auxiliary to the accuracy of heliometer measures in the shape of a reversing prism placed in front of the eye-piece, between the latter and the observer’s eye. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z Double-Image Micrometers with Divided Lenses.—Various micrometers have been invented besides the heliometer for measuring by double image. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z The inventor claimed that it would supersede the heliometer, but it has never done anything for astronomy. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z The present writer has successfully used a similar plan in measuring position angles of a Centauri with the heliometer, viz. by placing circular diaphragms on the two segments of the object-glass. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z These require extension, because the differential methods of the heliometer and the camera cannot otherwise be made absolute. History of Astronomy This lens is divided and mounted like a heliometer object-glass; the separation of the lenses produces the required double image, and is measured by a screw. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z Nor is it difficult to imagine the probable course of reasoning which led Bessel to select the model of his new heliometer. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z There are three methods in which this heliometer can be used. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z To sum up briefly the history of the development of the heliometer. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z In 1888-9, at the Cape, he observed the minor planets Iris, Victoria, and Sappho, and secured the co-operation of four other heliometers. History of Astronomy When the scales and position-circle of the heliometer have been set to these readings, the comet and the selected comparison-star appear together in the field of view. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z Thus, for refined purposes, it cannot be assumed with any certainty that the instantaneous scale-value of the heliometer is known, or that it is a function of the temperature. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z |
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