190 HOWARD E. PULLING 



be served by attempting a brief exposition of che scope of each 

 general field with a few notes on some of the essential working 

 features of the instruments so that, with the aid of the dis- 

 cussions to which references are made, those interested may 

 be aided in their selection. 



/. Radiometry'" 6 



Experience has shown that all energy is completely trans- 

 formable into heat energy — one of the principles upon which 

 thermodynamics is based. Radiometry consists in converting 



36 Boys, C. V., Preliminary note on the radio-micrometer, a new instrument 

 ior measuring the most feeble radiation. Proc. Roy. Soc. London 42: 189-193. 

 1887. 



Idem. The radio-micrometer. Phil. Trans. Roy. Soc. London 180A: 159- 

 186. 1889. 



Wilson, W. E., The thermal radiation from sun spots. Proc. Roy. Soc. 

 London 55: 246-249. 1894. 



Nichols, E. F., A method for energy measurements in the infra-red spectrum 

 and the properties of the ordinary ray in quartz for waves of great wave length. 

 Phys. Rev. 4: 297-313. 1897 



Abbot, C. G., Ann. Astrophys. Obs. Smithsonian Inst, 2: 1908; 3. 1913. 



Langley, S. P., The bolometer and radiant energy. Proc. Amer. Acad. Sci. 

 16: 342-358. 1881. 



Idem Ann. Astrophys. Obs. Smithsonian Inst, 1. 1902. 



Coblentz, W. W., Instruments and methods used in radiometry. I. Bull. 

 U. S. Bur. Standards 4: 391^60. 1908. 



Idem. II. Bull. U. S. Bur. Standards 9: 7-63. 1913. 



Idem. Measurements on standards of radiation in absolute units. Bull. 

 U. S. Bur. Standards 11: 87-100. 1915. 



Idem. Constants of spectral radiation of a uniformly heated enclosure or 

 so-called black body. I. Bull. U. S. Bur. Standards 10: 1-77. 1914. 



Idem. II. U. S. Standards 13: 459-477. 1916. 



Hyde, E. P., and F. E. Cady, On the determination of the mean horizontal 

 intensity of incandescent lamps by the rotating lamp method. Bull. U. S. Bur. 

 Standards 2: 415-437. 1906. 



Idem. On the determination of the mean horizontal intensity of incandescent 

 lamps. Bull. U. S. Bur. Standards 3: 357-369. 1907. 



Coblentz. W. W., and W. B. Emerson, Studies of instruments for measuring 

 radiant energy in absolute value. An absolute thermopile. Bull. U. S. Bur. 

 Standards 12: 503-551. 1916. 



Abbot, C. G., and L. B. Aldrich, The pyranometer — an instrument for 

 measuring sky radiation. Smithsonian Misc. Coll. 66: No. 7. 1916. 



Idem. On the use of the pyranometer. Smithsonian Misc. Coll. 66: No. 

 11. 1916. 



