Based on a robust, phenomenological model for the growth of a system parameter, a relation is derived to test the evolution of such a parameter through several distinct stages. It is found that data defining the acknowledged major changes in the evolution of earth, the life on it, and cultural and technological growth, conform to this model. The nature of these altering events indicates that information is the parameter involved, suggesting an unrecognized behavior in the Second Law of Thermodynamics.

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Hall effect measurements have been used to determine the two Hall constants and the magnetic properties of nickel films less than 100 A thick at room temperature. The extraordinary Hall constant R1 is found to be very much larger than in bulk nickel. In the thicker films, R1 shows the resistivity dependence predicted by Karplus and Luttinger. For the thinner films, the deviation of the measured initial Hall slope from the value thus predicted is taken as a measure of the hardness of magnetization in the direction normal to the film plane. The saturation magnetization obtained in this manner, and its variation with film thickness, agree fairly well with values found by other methods. For our thinnest films the direction normal to the film plane is one of very hard magnetization.

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Faraday rotation measurements on ferrimagnetic oxides have so far been limited to single crystals which are rendered transparent by grinding. In the present studies films of NiFe20. and CoFe20. of thickness 1000-8000 ..t, suitable for optical studies are prepared by oxidizing films of the alloys NiFe2 and CoFe2 sputtered on silica substrates. The Faraday rotation is determined with the film magnetized along axes both normal and parallel to its surface. Using the latter arrangement, optical hysteresis loops are recorded and chec~ed against those obtained with a vibrating sample magnetometer. The dep~ndence of loop shape and coercive force on film thickness and oxidation temperature is studied.