wpo - quasi equatorial mount - Crawford Dobsonian

  astro-optics page text & images [c]Maurice Gavin 1988/2001- BAAJournal -1988 Aug v98,#5, p268/9

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Meeting Report - Ordinary meeting of BAA -1988 March 30 at Scientific Societies Lecture Theatre - Savile Row London

Crawford-Dobsonian mount:   Maurice Gavin then described how a telescope on a Dobsonian mounting could be given a equatorial motion by utilising a technique first used by the Earl of Crawford in the 19th century. A piece of cord was attached to the telescope near the eyepiece and the other end secured to the ground at a point in the north-south line. A weight was attached to the telescope to tension the line which then constrained the instrument to move in an equatorial fashion.  Martin Ratcliffe pointed out that a similar technique had been used to impart a limited equatorial movement to the Earl of Rosse's 1.8 m (72") reflector.

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