miscellanea The P 4 SR index-a critique of a recent criticism
In the October 1967 issue of this Journal there appeared a paper, entitled 'Assessing the Heat Stress and Establishing the Limits for Work in a Hot Mine' (Wyndham, Allan, Bredell, and Andrew, 1967), in which an account was given of an investigation conducted underground at Mount Isa Mine in Queensland. The purpose of the investigation was twofold: to determine which of three commonly used indices of heat stress wet-bulb temperature, corrected effective temperature, or the P4SR index predicts most accurately the effects on workmen underground of the several factors concerned in heat stress, and to decide, in terms of the selected index, at what level of heat stress the length of shift should be reduced or work should cease. The reason for undertaking the enquiry, despite the fact that heat-work tolerance has been investigated many times before, is stated by Professor Wyndham and his co-authors (p. 256,1 col. 1) to be that:
The Globe Thermometer in Studies of Heating and Ventilation
The effects of radiation and convection on the globe thermometer have been studied. Equations have been obtained, and alignment charts constructed, for the calculation of mean radiation intensity and of equivalent temperature from readings of the globe thermometer, air temperature and air velocity. The accuracy of these methods has been tested on observations made under industrial conditions. Taking direct thermopile observations as the standard, the mean radiation intensity values calculated from globe thermometer readings had an average error of 1·2 B.Th.U. per sq. ft. per hour. With eupatheoscope readings as standard, equivalent temperature estimates had a mean error of 1·2°. It is concluded that, while globe thermometer readings alone are unreliable as indications of the effects of the thermal environment, valuable results can be obtained by using the instrument along with an ordinary thermometer and a silvered kata-thermometer.
Science of Ventilation and Open-air Treatment
DURING the war it was found that the physical condition of many of our young men was far from satisfactory, and there can be but little doubt that one of the contributory causes to this state of affairs was the ill-ventilated dwellings and factories in which such men frequently had to live and work, combined with a lack of opportunity or disinclination to take exercise. For example, in one region of England, of 200 youths of eighteen to twenty years of age examined.and rejected, no fewer than eighty-five failed to pass on account of poor physique and other physical defects.