 | Frederick Walter Simms - 1834 - 134 pages
...nor an altitude of the sun, with the sea horizon, can be taken backwards; because the dark-glasses at that angle prevent the reflected rays of light...and backwards. By the same means the errors of the dark-glasses are also corrected ; for, if they increase the angle one way, they must diminish it the... | |
 | Frederick Walter Simms - 1834 - 124 pages
...observe forwards first, where the whole range is without interruption; whereas, in that back' wards, you will lose sight of the reflected image about that...and backwards. By the same means the errors of the dark-glasses are also corrected; for, if they increase the angle one way, they must diminish it the... | |
 | Frederick Walter Simms - 1836 - 160 pages
...them, the discordant one must not on any account be omitted, but a fair mean must always be taken. angle to be taken is quite unknown, to observe forwards...and backwards. By the same means the errors of the dark-glasses are also corrected ; for, if they increase the angle one way, they must diminish it the... | |
 | Frederick Walter Simms - 1844 - 178 pages
...instrument, when compared with the sextant, are chiefly these : the observations for finding the index error are rendered useless, all knowledge of that being...and those of the indexglass very nearly. But what is still of more consequence, the error of the centre is perfectly corrected by reading the three branches... | |
 | John F. Heather - 1849 - 208 pages
...instrument, when compared with the sextant, are chiefly these: the observations for finding the index error are rendered useless, all knowledge of that being...quantity. This also perfectly corrects the errors of the horizon glass, and those of the index glass very nearly. But what is of still more consequence, the... | |
 | John Fry Heather - 1849 - 202 pages
...instrument, when compared with the sextant, are chiefly these : the observations for finding the index error are rendered useless, all knowledge of that being...for if they increase the angle one way, they must dimmish it the other way by the same quantity. This also perfectly corrects the errors of the horizon... | |
 | Frederick Walter Simms - 1850 - 184 pages
...instrument, when compared with the sextant, are chiefly these : the observations for finding the index error are rendered useless, all knowledge of that being...put out of the question, by observing both forwards aud backwards. By the same means the errors of the dark glasses are also corrected ; for, if they increase... | |
 | Sir Henry Edward Landor Thuillier - 1851 - 826 pages
...nor an altitude of the sun, with the sea horizon, can be taken backwards ; because the dark-glasses at that angle prevent the reflected rays of light...and backwards. By the same means the errors of the dark-glasses are also corrected ; for, if they increase the angle one way, they must diminish it the... | |
 | John Fry Heather - 1859 - 198 pages
...instrument, when compared with the sextant, are chiefly these : the observations for finding the index error are rendered useless, all knowledge of that being...quantity. This also perfectly corrects the errors of the horizon glass, and those of the index glass very nearly. But what is of still more consequence, the... | |
 | 1860 - 936 pages
...observations for finding the index error are rendered useless, all knowledge of that being put ont of the question by observing both forwards and backwards....quantity. This also perfectly corrects the errors of the horizon glass, and those of the index glass very nearly. But what is of still more consequence, the... | |
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... well as any other; for the rays incident on the index-glass will pass through the transparent half of the horizonglass, without much diminution of their brightness. " The advantages of this instrument, when compared with the sextant, are chiefly these... 
