52 CHARLES GRIFFIN & CO.'S PUBLICATIONS. 



SECOND EDITIOX. With very Numerous Illustrations. Handsome Cloth, 6a. 

 Also Presentation Edition, Gilt and Gilt Edges, 7s. 6d. 



THE THRESHOLD OF SCIENCE: 



A VARIETY OF EXPERIMENTS (Over 400) 



ILLUSTRATING 



SOME OF THE CHIEF PHYSICAL AND CHEMICAL PROPERTIES OF SURROUNDING OBJECTS, 

 AND THE EFFECTS UPON THEM OF LIGHT AND HEAT, 



BY 



C. R. ALDER WRIGHT, D.Sc., F.R.S., 



Lecturer on Chemistry and Physics in St. Mary's Hospital Medical School, London. 



%* To the NEW EDITION has been added an excellent chapter on the 

 Systematic Order in which Class Experiments should be carried out for 

 Educational purposes. 



"Its capital Index, its popular phraseology, its range of subjects, and 

 numerous Illustrations, suggest three uses which Dr. Alder Wright's Threshold 

 of Science will serve : 



" 1. It isa CAPITAL LIBRARY BOOKfor Teachers preparing simple object-lessons. 



"2. In the HOME LIBRARY it would be a practical ENCYCLOPEDIA of Science. 



''3. Finally, the book is a WORKING BOOK ; every point taken up has its 

 accompanying experiment often a MOST USEFUL one of which full details are 

 given ." /Schoolmaster. 



"Anyone who may still have doubts regarding the value of Elementary 

 Science as an organ of education will speedily have his doubts dispelled, if he 

 takes the trouble to understand the methods recommended by Dr. Alder 

 Wright. The Additions to the New Edition will be of great service to all 

 who wish to use the volume, not merely as a ' play-book,' but as an instrument 

 for the TRAINING of the MENTAL FACULTIES." Nature. 



"A FIRST-RATE BOOK to place in the hands of a boy." Educational Times. 



" An ADMIRABLE COLLECTION of Physical and Chemical Experiments . . . 

 a large proportion of these may be performed at home without any costly 

 apparatus." Journal of Education. 



" The work is quite as instructive as it is entertaining. . . . The 

 language throughout is clear and simple." School Guardian. 



" Will teach the young experimentalist to USE His HANDS, and last, but not 

 least, to THINK FOR HIMSELF." Industries. 



" Just the kind of book to add to a school library." Manchester Guardian. 



"Dr. Alder Wright has accomplished a task that will win for him the 

 hearts of all intelligent youths with scientific leanings. . . . Step by step 

 the learner is here gently guided through the paths of science, made easy by the 

 perfect knowledge of the teacher, and made flowery by the most striking and 

 curious experiments. Well adapted to become the TREASURED FRIEND of many 

 a bright and promising lad." Manchester Examiner. 



" From the nature of gases to the making of soap-bubbles, from the freezing 

 of water to the principles of ' pin-hole ' photography, Dr. Alder Wright's book 

 is an authority." Liverpool Mercury. 



LONDON: EXETER STREET, STRAND. 



