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The tests of performance of the modified thin-lens magnetic spectrometer using ring-detection have been extended using improved mechanical controls of detector position. The results show only a small improvement over the performance obtained previously in this laboratory. We conclude that the limit of performance with the thin-lens magnet has been reached. Further improvement: may be achieved only with a precision-wound magnet coil which will produce a completely symmetric field. The decay of [formula omitted] has been investigated using the modified thin-lens spectrometer, a scintillation spectrometer and beta-gamma, conversion-electron gamma coincidence techniques. The results support the simpler decay scheme proposed by Van Wijngaarden and Connor. The beta decay has three components with end-point energies and intensities of 659+3 kev(67 .3%), 411 kev (2.5%) and 89 kev (30.3%), estimated from the energy level intensity balances in Ba¹³⁴. These intensity balances show discrepancies of less than 3% of the total decay intensity. The conversion coefficients, calculated from the conversion electron and gamma-ray intensities lead to the following multipolarity identifications for the transitions in Ba¹³⁴; 473 kev (Ml or E2)j 563-569 kev (Ml or E2), 605 kev (E2), 797-803 kev (E2), 1036 kev (Ml or E2), 1168 kev (E2) and 1366 kev (E2), in agreement with other work. The Ml or E2 character of the 473 kev and 1036 kev transitions makes it possible to assign a spin of 3+ or 4+ to the 1641 kev level which was uncertain before. An unsuccessful search for evidence of a 960 kev gamma-ray reported by others puts an upper limit of 0.2% on its intensity. / Science, Faculty of / Physics and Astronomy, Department of / Graduate