Translator's Note 



Mail; The Pond, Industrial Chemistry and 

 the two chapters on the Bluebottle in The 

 English Review; and The Harmas, The Pond 

 and Industrial Chemistry in the New York 

 Bookman. The others are new to England 

 and America, unless any of them should be 

 issued in newspapers or magazines between 

 this date and the publication of the book. 



I wish once more to thank Miss Frances 

 Rodwell for her assistance in the details of 

 my work and in the verification of the many 

 references ; and my thanks are also due to Mr. 

 Edward Cahen, who has been good enough to 

 revise the two chemistry chapters for me, and 

 to Mr. W. S. Graff Baker, who has per- 

 formed the same kindly task towards the two 

 chapters entitled Mathematical Memories. 

 Alexander Teixeira de Mattos. 



Chelsea, 8 July, 1913. 



