Burke and Lowe 2) described a method for the measurement of neutron spectrum and temperature of a beam of neutrons based on transmission through various thicknesses of 1/ v absorbers. The analysis was done considering single collision phenomena. This, however, may not be true for large thickness of the absorber, which are necessary to obtain low values of transmission. Hence an experiment measuring the transmission through various thicknesses of silver in a beam of neutrons emerging from the CIRUS and APSARA reactors was undertaken. The experimental data were analysed both for single and multiple collision phenomena. It is seen that neglection of multiple scattering in the present experimental set-up gives rise to an error which is less compared to the error on the measured value of the temperature by single collision treatment. The emergent spectrum at CIRUS shows a temperature consistent with that obtained from a well thermalised reactor whereas in case of the swimming pool reactor APSARA, a temperature much higher than the physical temperature is obtained. However, this is consistent with the effective temperature of an equivalent homogenised reactor moderator with actual core parameters.