MAGNETO-OPTIC PHENOMENA OF IRON, NICKEL, AND COBALT. 
107 
The first of these series is described by Sissiogh in a paper in the ‘ Archives 
Neerlandaises,’ vol. 27. The experiments were made with an iron mirror, magnetised 
parallel to the reflecting surface; the amplitude /x and phase m of what Sissingh 
calls “the magneto-optic component of the reflected light ’ were measured for various 
angles of incidence. 
One result of the observations is the conclusion that /x, = /x^, and m, = nip ; that 
is, that for any given angle of incidence the magneto-optic component has the same 
amplitude and phase, whether the incident light be polarised in or perpendicularly 
to the plane of incidence. It is to be noticed that the phase of this component is 
defined as its retardation of phase calculated relatively to that component of 
ordinary metallic reflection which is polarised in the plane of incidence. The 
amplitude is reckoned on the supposition that the amplitude of the incident ray is 
unity. 
The accompanying figure shews the relation between the axes of coordinates and 
the principal directions for the incident and reflected rays, as defined by Sissingh. 
The standard ray for phase is — B. The standard ray for amplitude is — Aq/cos?, or 
— Bq, according as the incident light is polarised perpendicularly to or in the plane 
of incidence. 
X 
It will be convenient to denote by ^ the acceleration of phase of the magneto¬ 
optic component of the reflected ray calculated relatively to that componenl; ot 
ordinary metallic reflection which is polarised in the plane of incidence. 11 d be 
calculated from theory, and m from experiment, the theory and experiment will 
agree if S + ^n = 0° or 360° 
21. When the incident light is polarised in the plane of incidence, Ag = 0, and in 
formula (36) the incident ray is represented by — By, the magneto-optic component 
of the reflected ray by — A/cos7, and the component relatively to which phase is to 
be measured, by — B. Hence 
0. = vector angle of [A/Bcos?’]ao = o 
= vector angle of 
2.t.cA, (m/M) CV‘* ■“ H 7 ,,) 1 
cos-i -I- Mjm) (M — w)] 
(40). 
