**His** **paper** **on** **the** **variation** **of** **the** **specific** **heat** **with** **temperature**, **which** **appeared** **in** 1907, **was** **the** **first** **extension** **of** **Planck'****s** **fundamental** **hypothesis**, **and** **its** **verification** **in** **essentials** **is** **one** **of** **the** **most** **convincing** **arguments** **in** **its** **favour**.

**If** **we** **assume** **that** **the** **bolograph** **of** **solar** **energy** **is** **simply** **a** **graph** **of** **amorphous** **radiation** **from** **an** **ideal** **radiator**, **so** **that** **the** **con**- **Temperature** **stants** **cl**, **c** 2, **of** **Planck'****s** **formula** **determined** **terrestrially** **apply** **to** **it**, **the** **hyperbola** **of** **maximum** **intensity** **is** **XO** = 2, 921 **X** 10 7; **and** **as** **the** **sun'****s** **maximum** **intensity** **occurs** **for** **about** **X** =4900, **we** **find** **the** **absolute** **temperature** **to** **be** 5960° **abs**.

**Planck'****s** **views** **were** **elaborately** **developed**, **but** **his** **method** **of** **exposition** **told** **heavily** **against** **their** **acceptance**.