PREFACE, vii 



had introduced, with a view to show the important 

 " instructional value " of Botany as an " educational 

 weapon," in the opportunity which Botanical Lessons 

 afford the teacher of introducing ta his class a large 

 amount of useful information upon topics of the most 

 varied kind. Thus I find a lesson in pneumatics 

 apropos of pop-guns made of the stem of the 

 Elder ; an account of soap-making, and the method 

 of ascertaining specific gravities, in connexion with 

 the Olive order, represented in Britain by the Ash ; 

 how to analyse a Potato, under the Bittersweets ; an 

 account of wonderful bells, under the Bellflowers; 

 of glass-making, under the Saltworts, formerly burnt 

 for the sake of their alkaline salts ; of brewing, under 

 Hops; and the like. I have omitted such matter 

 because it would require more space than could be 

 afforded in a book of small cost, to be used by 

 private learners as well as by teachers; and also 

 because the variety of topics which a teacher may 

 thus introduce, and which his own intelligence may 

 suggest, is infinite. 



Professor Henslow's plan of employing " sche- 

 dules," designed to direct the attention of the pupil 

 at once to the most important points of structure, I 

 have adopted in my own class with much advantage. 

 Their use should be commenced as soon as the 

 first six chapters are thoroughly acquired. Any 

 printer would strike off a few hundred blank 



