Prof. A. F. Holleman

n levels. This is necessary for the proper design of shielding which will protect those working near the machine and also allow access to the various beams of radiation from targets. A detailed experimental programme is being prepared, and it is hoped that this synchrotron, which provides 7t'-mesons of energies up to at least 700 MeV., will add significantly to existing information on the nuclear interactions of high-energy particles. It is clear that the accumulation of events of interest in nuclear emulsions and cloud chambers is likely to be rapid.

• Rev. Sci. Instr. (the September 1953 issue is devoted to a description of the Brookhaven cosmotron). • Oliphant, M . L., Gooden, J. S., and Hide, G, S., Proc. Phys. Soc., 59 . 666 (1947) . ' .Vature, 169, 476 (1952) .

• tlibbard, L. u., Nucleonics , 7, No. 4, 30 (1950) ; see also The Engineer, 195, 271 and 305 (1953).