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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    “ will consequently appear larger than they a ought. The effect of magnifying,,power “ is, to occasion a relative increase of the “ vacancy between two stars that are very u near each other; but the ratio of the in- “ crease of the distance is not proportional “ to that of the power, and sooner or later comes to a maximum. The state of the u atmosphere is perhaps the most material i{ of the four conditions, as we have it not “ in our power to alter it. The effects of “ moisture, damp air, and haziness, (which “ have been related in a paper where the u causes that often prevent the proper “ action of mirrors were discussed,) show li the reason why the apparent distance of u a double star should be affected by a u change in the atmosphere. The altera- “ tion in the diameter of Arcturm, extend- “ ing from the first to the last of the ten “ images of that star, in the plate accom- “ panying the above-mentioned paper *, “ showrs a sufficient cause for an increase * See Phil. Trans, for 1803, p. 232, plate in.
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