40 SCIENCE. 



Ten additional varieties are supplied in the same way : — 



I large specimen of each kind, 10 in all, labelled . . . $ .30 



5 smaller specimens of each kind, 50 M " ... .75 



10 " " " " 100 " f * ... 1.50 



20 " " " " 200 " '* ... 2.50 



Orders for these specimens should be addressed to Prof. W. o 

 Crosby, Boston Society of Natural History, Boston, Mass. 



First Lessons in Minerals. {No. XIII.) 



By Ellen H. Richards, Instructor in Mineralogy, Massachusetts Insti- 

 tute of Technology. 4^ by 6 inches. Paper. 50 pages. Introduction 

 price, 10 cents. A valuable introduction to Guide No. XII. 



The outline of the lessons was first worked out with three successive 

 classes of children, from six to eight years old, just out of the Kinder- 

 garten. The lessons were then given to classes in two public schools 

 in the city of Boston. During the two years which have since elapsed, 

 they have been given to about one thousand children of the fourth 

 classes of several of the Boston Grammar Schools. They have also 

 been adopted by teachers in other places. Such changes have been 

 made as experience has shown to be desirable, and the Guide is now 

 presented in a form which can be recommended to teachers in general. 

 The specimens to illustrate Guide No. XIII. consist of large, 

 carefully selected cabinet specimens, with printed labels. It is desirable, 

 however, to have a specimen of each type for every pupil, or at least 

 for every two or three pupils. To meet this need, duplicate collections 

 of somewhat smaller specimens, numbered but not labelled, have been 

 prepared. 





50 specs. 



80 specs. 



125 specs. 



150 specs. 



Cabinet size, 



£2.00 



$4.00 



$8.00 



$10.00 



Student size, 2-5 colls. 



1. 00 ea. 



2.00 ea. 



4.00 ea. 



5.00 ea. 



« 6-10 " 



.90 ea. 



1.80 ea. 



3.60 ea. 



4.50 ea. 



The student collections are not sold singly. 



Other collections, adapted to more extended courses, are supplied as 

 follows : — 



Minerals. 50 specs. 100 specs. 150 specs. 



Cabinet size, $6.00 $15.00 $3000 



Student size, 200 5.00 10.00 



