The term “Orientation,” as applied to a structure of any kind, means the direction in which its principal line is laid out on the ground. Originally, as the word implies, orientation signified “eastwardness,” only, and had special reference to churches, because (in western Europe) practically all churches were built with the longer side laid out in an east-and-west direction. In some, the line is to True East, exactly; in others the axis lies at an angle of some degrees either to the northward or to the southward of True East. This divergence in either direction from the Orient is called “the angle of orientation.” Nowadays, the term “Orientation” has lost its original “Eastward” distinctiveness, and has become a general expression merely indicating “direction,” and may imply any point of the horizon, and not necessarily the eastward.
Originally the angle of orientation was measured from True East as a zero, but now it is reckoned from the Meridian, or North (true).
1 Technically speaking, an angle reckoned from thė Meridian is named an AZIMUTH, and is stated in degrees, minutes, and seconds of arc from 0° to 360° round the circle in the direction taken by the hands of a clock. This, the modern method of reckoning, is considerably the clearer and simpler.
An angular measurement reckoned from True East, or West is named an AMPLITUDE, and is stated in degrees up to 90° to the northward or up to 90° to the southward of East or West. Thus, it requires to be set down as “E—N” or “E—s”, as the case may be (and from West in like manner).
The term BEARING is often seen used in reference to a direction, but, strictly speaking, this is a nautical term, and refers properly to the Mariner’s (magnetic) Compass. It is the angle from Magnetic North, or Magnetic South for 90° each way towards East or West (magnetic), and requires to be stated as “N—E,” “N—w,” “S—E,” or “s—w” as the case may be. It should never be used in describing orientations, which infer a True, and not a Magnetic direction.
4 It may be remarked that there are, besides the Zodiacal stars, certain well-known bright stars that rise and set further north, along the horizon, than the Sun at the Summer Solstice, or that rise and set further south than the Sun at the Winter Solstice. These stars may possibly be connected with Orientation ; but there is as yet insufficient evidence of its occurrence.