| 释义 |
▪ I. stadia|ˈsteɪdɪə|
[Of obscure history; prob. derived from stadium, and perhaps from the plural stadia. Cf. F. stadia (Littré Suppl., with quot. of 1876).
It is doubtful in what country the word originated; the statement in the first quot. below lacks confirmation.]
An apparatus for measuring distance by optical means. a. Mil. An instrument consisting of a glass plate, or a brass plate with an opening of the form of an isosceles triangle, marked with figures showing the distance at which a foot- or horse-soldier will be when his image covers a certain height on the instrument held at arm's length. b. Surveying. An apparatus consisting of a rod or staff placed at one end of the distance to be measured and a pair of horizontal lines, hairs or wires on the diaphragm of a telescope placed at the other end. Also attrib. as in stadia hairs, stadia lines, stadia measurement, stadia method, stadia-rod, stadia-surveying, stadia telescope.
By British surveyors stadia is commonly used as equivalent to ‘stadia rod’; in the U.S. this use appears to be rare. The ‘stadia method’ has two varieties: in the one the staff is graduated and the telescope hairs fixed at a known distance apart; in the other the staff is of known length and the hairs are movable.
1865Mayer in Jrnl. Franklin Inst. Jan. 4 The idea to measure the distances by a scale and the micrometer of a telescope was proposed by an Italian engineer about 45 years ago, and the name of Stadia (scale) was given by him to that kind of measure. Ibid. 5 Construction of a Stadia. Ibid., To..compute the error of the reading on the Stadia scale. 1865S. W. Robinson Ibid. Feb. 74 The error of the stadia measurement has been found to be about one foot in 800 or 1000. Ibid. 75 A much more convenient arrangement than the rod and targets, is a flat surface of three or four inches width and the required length, painted in such a manner that the distance can be read to a foot by the observer himself. By the French this is called a stadia. 1871Trans. Amer. Inst. Min. Engin. I. 377 An extra pair of hairs for stadia purposes. 1890W. F. Stanley Surv. Instrum. 321 For convenience the tangent is more generally taken upon a graduated stadia or staff which is erected for measurement perpendicularly to the horizon. 1899W. G. Bligh Notes Instrum. Engin. Field-work 122 The telescope fitted with stadia lines on a stop glass. Ibid. 124 Stadia hairs are horizontal lines, either hairs fixed to the diaphragm or else marked on a stop glass. 1900H. M. Wilson Topogr. Surveying xii. 238 The stadia is a device for determining the distance of a point by means of a graduated rod, and the distance subtended on it by auxiliary wires in the telescope of a transit or alidade. Ibid., The term stadia surveying is used to include not only the measurement of the horizontal distance, but also the determination of heights by means of vertical angles observed to a fixed point on the rod.
▪ II. stadia
pl. of stadium. |