Prominent lines in simple spectra of elements. — The more prominent lines, in 

 simple spectra, easily excited with high intensity, are universally employed in spectroscopy, 

 refractometry, polarimetry, spectrophotometry, interferometry, and metrology either to 

 calibrate the wavelength scales of dispersing instruments or to make optical measurements 

 at various wavelengths. A brief tabulation of the wavelengths most commonly used for 

 these purposes is given in Table 619, where numerical values of wavelengths and approxi- 

 mate relative intensities by elements are followed by graphical presentation (fig. 30). The 

 spectral range is restricted to that easily observed photographically in air (2000 to 

 10000 A). Values of wavelengths are quoted from the M.I.T. Wavelength Tables (John 

 Wiley & Sons, New York, 1939) and relative intensities in individual spectra are estimated 

 from arc spectrograms made at the National Bureau of Standards. 



TABLE 619.— WAVELENGTHS (IN ANGSTROMS) AND RELATIVE 

 INTENSITIES OF PROMINENT LINES IN SIMPLE SPECTRA 



SMITHSONIAN PHYSICAL TABLES 



