CONTENTS. xi 



ON THE AGE OF THE SUN'S HEAT 349 



Reprinted 'by permission from ' ' Macmillari s Magazine, " 

 March, 1862. 



PART I. ON THE SECULAR COOLING OF THE SUN . . 351 

 PART II. ON THE SUN'S PRESENT TEMPERATURE . . 361 



PART III. ON THE ORIGIN AND TOTAL AMOUNT OF 

 THE SUN'S HEAT , 363 



ON THE SUN'S HEAT 369 



A Friday evening Lecture delivered before the Royal 

 Institution of Great Britain on January 21, 1887 



ELECTRICAL MEASUREMENT 423 



Address before Section of Mechanics at the Conferences 

 held in connection with the Special Loan Collection 

 of Scientific Apparatus at the South Kensington 

 Museum, May 17, 1876. 



INDEX 457 



