scientific apparatus and instruments, namely, all portable instruments, namely, pyrometers, thermometers, anemometers, hygrometers, apparatus for detecting and analyzing exhaust gases, apparatus for detecting and analyzing flue gases, sound level meters, apparatus for analyzing mine air quality, spectroscopes and astronomical spectrographs, radar guns for police work, sporting events, and laboratory use, and noise spectrum analyzers for measuring of different physical, chemical, and other par...