An Instrument for Observing Hour Angle or Latitude Directly
The instrument described in this article has been under development at the University of California for several years. It breaks the two-hundred year old tradition that a navigator, in order to find his position, must measure an altitude and then solve a spherical triangle. The instrument gives directly either hour angle or latitude. The observed hour angle, combined with the proper Greenwich hour angle from a watch or chronometer, yields the longitude. Usually such latitudes and longitudes are not independent but lie along a Sumner line as in the case of reduced sextant observations. The advantage lies in the elimination of practically all computation or use of tables. The instrument has the same weight as the average sextant, and with the same amount of practice, is as easy to observe with. It is called a Spherant.