Practical observations on telescopes.

  • William Kitchiner
Date:
1815
Catalogue details

Licence: Public Domain Mark

Credit: Practical observations on telescopes. Source: Wellcome Collection.

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    the original pencil to that of the pencil which enters the eye. The degree in which magnifying power may be advantageously applied, depends so much on the perfection of the telescope and the state of the atmosphere, that it is hardly possible, by any general rules, to fix precise limits to it: but, to afford an oppor¬ tunity of trying this and many other enter¬ taining experiments, the day eye-piece should have a pipe-drawer; and the screw, which receives the tube containing the two first glasses, should be the same as the screw which fixes the eye-drawer to the telescope: and the two first eye-glasses should be made to separate (by a sliding tube within the pipe-drawer) from the third and fourth. This will give a very pleasing variety, and be extremely convenient to those who wish to obtain a certain, exact degree of magnifying power. For large adjustments, and also that the telescope may be used for near objects, it should have a sliding tail-piece; and the tooth and pinion for the fine adjustment
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