Il6 THE TEACHING BOTANIST 



ground, and India ink, applied with a brush, for the 

 lines. This method is inexpensive, easy, and gives a 

 pleasing combination. If one wishes to use colors, 

 water-colors are best ; but a fair substitute may be 

 found in colored crayons, which may be prevented 

 from rubbing by a previous immersion in melted soft 

 paraffin until the bubbles cease to come off, or by 

 spraying the drawing through an atomizer with a weak 

 solution of gum arabic. 1 



The best method known to me of hanging diagrams 

 when in use has already been described (see Fig. 5). 

 For storing they should be as nearly as possible of one 

 size, of which the Kny series is a standard (84 x 68 cm.). 

 They may then be very conveniently kept in shallow, 

 upright cases built against the wall, a foot above the 

 floor, with the front hinged on the bottom so as to drop 

 forward a few inches at the top, as shown in the accom- 

 panying diagrammatic cross-section ; a chain keeps the 

 front from falling too far (Fig. 11). 



Another very valuable class of illustrations includes 

 those in special monographs or technical papers ; and 

 where a good library is available, free use should be 

 made of these original sources of information. 



Many teachers would probably place models before 

 diagrams in illustrative value, and chiefly because these, 



1 Another method is fully described, and there are other valuable 

 hints upon this subject, in "Natural History Charts and Illustrations," 

 by J. W. Harshberger, in Education, April, 1897. 



