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The cross sections of the electron impact ionization and dissociative ionization of CO, CH 4 and C 2 H 2 have been measured for electron energies from threshold to 600 eV. The present values agree with the previous measurements where a complete collection of the resulting ions has been demonstrated experimentally. However, for the processes where no complete collection has been demonstrated, the present results are usually higher if the ions are produced with higher kinetic energy. The present measurement demonstrates the complete collection of the ions experimentally and the results are thus believed to be reliable. The disagreement between the present results and the previous ones is explained by noting the kinetic energy distributions of the fragment ions.

Numerical solutions for fully nonlinear two-dimensional irrotational free-surface flows form the basis of this study. They are complemented and supported by a limited number of experimental measurements. A solitary wave propagates along a channel which has a bed containing a cylindrical bump of semicircular cross-section, placed parallel to the incident wave crest. The interaction between wave and cylinder takes a variety of forms, depending on the wave height and cylinder radius, measured relative to the depth. Almost all the resulting wave motions differ from the behaviour which was anticipated when the study began. I n particular, in those cases where the wave breaks, the breaking occurs beyond the top of the cylinder. The same wave may break in two different directions: forwards as usual, and backwards towards the back of the cylinder. In addition small reflected waves come from the region of uniform depth beyond the cylinder. Experimental results are reported which confirm some of the predictions made. The results found for solitary waves are contrasted with the behaviour of a group of periodic waves.

A new, well-defined metal vapor device called the heat-pipe oven has been developed on the basis of the heat pipe, a heat conductive element designed by Grover and his co-workers in Los Alamos. It continuously generates homogeneous vapors of well-defined temperature, pressure, and optical path length. The vapor is confined by inert gas boundaries which remove the window problem and allow a direct pressure measurement without relying on vapor pressure curves. Due to the continuous evaporation and condensation the vapor purifies itself during operation.

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