A possible source of error in the determination of symmetry from optical extinction-angles

During an optical examination of many mesolite crystals with a view to a determination of their symmetry, the author was puzzled to find that whereas mesolite has generally been described as anorthic, on optical evidence, he could detect no trace of inclined extinction in the prism zone. A. Cavinato (1926) 1 and G. Ceshro (1909) 3 had already made similar observations. Further study revealed the probable causes of the discrepancies, and as these sources of error, and the precautions necessary for their avoidance, receive little or no mention in the principal text-books, an account of them might be of some use.

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A Collecting Bottle Especially Adapted for the Quantitative and Qualitative Determination of Dissolved Gasses, Particularly Very Small Quantities of Oxygen

Illinois Natural History Survey Bulletin ◽

10.21900/j.inhs.v11.367 ◽

1918 ◽

Vol 11 (1-10) ◽

pp. 577-578

Author(s):

Edwin Powers

Keyword(s):

Dissolved Oxygen ◽

Recent Work ◽

Oxygen Content ◽

Potassium Iodide ◽

Free Water ◽

Sources Of Error ◽

Winkler Method ◽

Source Of Error ◽

Qualitative Determination

One of the sources of error in the Winkler method for the determination of dissolved oxygen in water, especially where the oxygen content is low, is the diffusion of oxygen into the water before and during the introduction of the chemicals. Another source of error is the mixing of the manganous chloride with the potassium iodide-alkali solution at the surface of the water, the chemicals adhering to the pipettes introducing these reagents having washed off at the topof the bottle, where they react with the oxygen present. In recent work involving the oxygen-free water apparatus described by Shelford in the preceding article of this volume, it was found especially desirable to eliminate the above sources of error. This was accomplished by a special bottle which allows the collecting of samples and the introduction of the chemicals without exposing the samples to air during the operation.

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Reply by Alan T. Herring to discussion by Lewis R. Tucker

Geophysics ◽

10.1190/1.1486592 ◽

1972 ◽

Vol 37 (5) ◽

pp. 907-907

Author(s):

Alan T. Herring

Keyword(s):

Gravity Field ◽

Focal Point ◽

Critical Step ◽

Sources Of Error ◽

Geophysical Interpretation ◽

Regional Gravity ◽

Source Of Error

The focal point of Mr. Tucker’s criticism is a feeling that we have not properly identified our assumptions or given the probable uncertainties of our interpretation proper attention. I disagree; over 75 percent of the text of our note is devoted to the discussion of probable sources of error. Mr. Tucker’s discussion brings to light no source of error which has not been mentioned already in our note. Mr. Tucker is quite right to point out, as we have, the assumptions and uncertainties inherent in any geophysical interpretation. The determination of a regional gravity field is indeed a critical step, but as we have pointed out, a step which can be constrained by geologic knowledge and reasonable geologic assumptions.

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Sources of Error in the Determination of Metabolic Rate

Scandinavian Journal of Clinical and Laboratory Investigation ◽

10.3109/00365516109137267 ◽

1961 ◽

Vol 13 (2) ◽

pp. 180-185 ◽

Cited By ~ 3

Author(s):

J. Georg ◽

K. Mellemgaard

Keyword(s):

Metabolic Rate ◽

Sources Of Error

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THE DISTRIBUTION OF IONIZATION ALONG UNDERDENSE METEOR TRAILS

Canadian Journal of Physics ◽

10.1139/p64-189 ◽

1964 ◽

Vol 42 (11) ◽

pp. 2035-2047 ◽

Cited By ~ 7

Author(s):

D. W. Rice ◽

P. A. Forsyth

Keyword(s):

Upper Atmosphere ◽

Sources Of Error ◽

Signal Characteristics ◽

Radio Signals ◽

Meteor Trails

Attempts to use the decay of radio signals reflected from individual meteor trails to study the upper atmosphere have revealed a puzzling inconsistency in the signal behavior. An earlier paper pointed out that this inconsistency remained even when the previously postulated sources of error were eliminated. As a result, an irregularly ionized trail model was proposed and shown, by calculation of signal characteristics, to be capable of accounting for the observations. This paper presents results of a new experiment which permitted the determination of the ionization profiles as the meteor trails were formed. The predicted irregularities were found, even for trails which exhibited apparently "ideal" underdense signal characteristics.

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