The scientific papers of Sir William Huggins (1909)
Huggins, William, Sir, 1824-1910, Huggins, Lady, d. 1915 · London, W. Wesley and son · leaf 201
tance of 2 feet 6 inches within the principal focus. Tubeswere fixed by screws over these holes, and in these tubes slide suitable holdersfor carrying electrodes or vacuum-tubes. The final adjustment was tested bythe comparison of the bright lines of magnesium and the double line of sodiumwith the… … seems to be impossible, for even a minute motion of the spark or other sourceof light for comparison has the effect of throwing the light to one side,without the slit; so that, as long as the comparison spectrum is seen, therecan be no doubt that the direction of the light for comparison, as it…
Astronomy
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