The London, Edinburgh and Dublin philosophical magazine and journal of science . must now be added :— B. 1. The middle line is a symmetrical triple, the distancebetween the components being one-fourth that of the outerlines/ and hence also proportional to the strength of field. 2. The relative intensity of the components varies for dif-ferent substances and for different lines of the same substance;and accordingly the group may appear as a single line or adouble or a triple. 3. The outer lines are unsymmetrical, but are sym-metrically placed with respect to the middle Jine. Thedistance between
The London, Edinburgh and Dublin philosophical magazine and journal of science . must now be added :— B. 1. The middle line is a symmetrical triple, the distancebetween the components being one-fourth that of the outerlines/ and hence also proportional to the strength of field. 2. The relative intensity of the components varies for dif-ferent substances and for different lines of the same substance;and accordingly the group may appear as a single line or adouble or a triple. 3. The outer lines are unsymmetrical, but are sym-metrically placed with respect to the middle Jine. Thedistance between the components is usually one-fourth thatbetween the outer lines/ but is in some cases one-sixth. 4. The intensity of the components varies for differentspectral lines, and these variations do not always correspondto those of the central line. The outer groups may accor-dingly appear as single or double or triple or multiple lines. Fig. 1 represents a plan of the arrangement of apparatus* Communicated by the Author. On Radiation in a Magnetic Field. 349 bo *H W; ^^ t: 77^^. C^—^ PA//. 1%. S. 5. Vol. 45. No. 275. J^>v7 1898. 2 B 350 Prof. A. A. Michelson on employed in the investigation. S is the source of light, eithera small hand-blowpipe with a bead of the substance to beexamined in the flame, or a vacuum-tube, which is usuallyplaced in a metal box (for heating) of such form as to permita close approach of the pole-pieces P of an of these is bored out to permit examination of the axialra}\ The light from S undergoes a preliminary analysis bythe spectroscopic train (two bisulphide prisms), the radiationto be investigated being isolated by the slit s. It then entersthe interferometer, one of the mirrors of which, M, is move-able on ways so accurately ground that no readjustment isnecessary in any part of its path ; that is, the mirror remainsso nearly parallel with itself that the interference-fringes(concentric circles) are always as clear as possible
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
