Summarizes the present state of sea-floor spreading theory, elaborates upon some apparent consequences,and makes some suggestions about future education in the earth sciences. The author concludes that the future of the earth sciences looks bright and exciting. (RR)

An optical dectector consisting of a high-speed PIN diode and a transistor was evaluated for use in student experiments with a pulsed-ruby laser. Pulses with 36-nsec risetimes were clearly resolved. (LC)

A search is in progress for copies of Copernicus' 1543 publication "On the Revolutions of the Celestial Spheres." The history of each copy (215 found thus far) is being analyzed to offer insights into the past. For example, the futility of the Inquisition's attempt to censor the book was chronicled. (Author/JN)

The generator set of a group is the subset of the set of elements of the group. The nature and use of generator sets is discussed, focusing on generator sets for the noncubic symmetry point groups containing one, two, and three symmetry elements. (JN)

A fixed amount of an ideal gas is confined in an adiabatic cylinder and piston device. The relation between temperature and volume in initial/final phases can be derived from the first law of thermodynamics. However, the relation can also be derived based on kinetic models. Several of these models are discussed. (JN)

A 1-hour laboratory exercise which demonstrates the correctness of the relativistic relationship between energy and momentum is described. In addition, a value of Planck's constant and the velocity of light can be derived. (JN)

Describes construction/use of a device to simulate structures produced in fault zones of dominantly strike-dip motion. Apparatus modifications allow simulation of transtension and transpression as well as pure strike-slip fault motion. Illustrates formation of several structures using the apparatus, comparing them with natural examples. Includes…

Discusses ambiguities of the accepted definition of the chelate effect, suggesting that it be defined in terms of experimental observation rather than mathematical abstraction. Indicates that the effect depends on free energy change in reaction, ligand basicity, pH of medium, type of chelates formed, and concentration of ligands in solution. (JN)

An overwhelming biomass of microscopic organisms is forcing revision of the conventional notions of what eats what in the seas. The nature and importance of these marine microorganisms are discussed. (JN)