 | John Louis Emil Dreyer, Ralph Copeland - 1884 - 274 pages
...practical difference enters into consideration that has been particularly experimented on by Mr. Russell, of Sydney, viz., that the correction of an object-glass...that the somewhat over-corrected object-glass of the 15-inch equatoreal at Dun Echt has been materially improved by separating its lenses £ of an inch,... | |
 | John Michels (Journalist) - 1884 - 860 pages
...Sydney; viz., that the correction of an object-glass may be lessened by separating the lenses: so that an over-corrected object-glass may be adjusted to...that the somewhat over-corrected object-glass of the 15inch equatorial at Dun Echt has been materially improved by separating its lenses 0.2 of an inch,... | |
 | John Michels (Journalist) - 1884 - 848 pages
...difference enters into consideration, one which has been particularly experimented on by Mr. Hussell of Sydney; viz., that the correction of an object-glass may be lessened by separating the lenses: so that an over-corrected object-glass may be adjusted to any desired extent, while one that is under-corrected... | |
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... average glass by Cooke or Grubb, and to a less extent by Clark, appears over-corrected, while one of Schroder's and some of the Munich glasses are under-corrected. But here an important practical difference enters into consideration that has been... 