An Economical System for 



Country House Lighting and 



Laboratory Heating 



The 

 Willett 

 Light 



For economy, efi&ciency, and convenience 

 the ideal lighting system for the Farm, 

 Country House, Estate, etc. is the 

 Willett Light. 



The most remotely situated dwelling or 

 building of any description can be 

 illuminated with this bright, cheerful 

 light at a very low cost. 

 The Willett Petrol Air Gas system is 

 largely used for laboratories. With 

 adapted burners it can be used for every 

 laboratory operation usually undertaken 

 with the aid of coal-gas. 

 The Generator is entirely automatic in 

 action, and absolutely devoid of com- 

 plicated mechanism. The slight power 

 needed is derived from weights on the 

 principle of the grandfather's clock. No 

 expert knowledge whatever is necessary. 

 To instal the Willett Light means a great 

 saving in labour. 



A demonstration of the Willett Light 

 wiU be gladly given at the showrooms. 

 Write today for booklet "A.T." and 

 learn how really economical is this 

 efl&cient and convenient system. 



W. Willett, 39n, Sloane Sq., London, S.W. 



TeleplioM : Kensington 4660 (4 lines). 



The House with over 40 years reputation 



The University of Chicago Press 



THE ORIGIN OF THE EARTH 



By 



THOMAS CHROWDER CHAMBERLIN 



Head of the Department of Geology in the University of Chicago 



(Fourth volume in the University of Chicago Science Series) 



This book, by one of the leading geologists of the world, sets forth the disclosures 

 that led to the rejection, one after another, of the older views of the origin of our planet, 

 the futile attempts then made to emend these or to build others upon the same foundations, 

 the final rejection of all these, and the construction of a radically new view based on a 

 new dynamic foundation. The later chapters of the book treat of the early stages of 

 the earth and of the way in which its leading processes took their start from their cos- 

 mogonic antecedents, these being held to be essential factors in the genesis of the planet. 

 The beginning of the inquiry is set forth in the Introduction; the successive chapters 

 are entitled: "The Gaseous Theory of Earth-Genesis in the Light of the Kinetic Theory 

 of Gases"; "Vestiges of Cosmogonic States and their Significance"; "The Decisive 

 Testimony of Certain Vestiges of the Solar System" ; "Futile EflEorts" ; "The Forbidden 

 Field" ; "Dynamic Encounter by Close Approach" ; "The Evolution of the Solar Nebula 

 into the Planetary System" ; "The Juvenile Shaping of the Earth" ; "Inner Reorganiza- 

 tion of the Juvenile Earth"; "Higher Organization in the Great Contact Horizons." 

 xii -f 272 pages, 12mo, cloth; 6« net 



The Cambridge University Press 



Agents for the British Empire 



London, Fetter Lane 



