HYGIENIC REQUIREMENTS IN PRINTING 547 



should be a rationalization of these printed letter-forms that have come 

 down to us in such a happy-go-lucky fashion, and it is to be hoped that 

 either the Carnegie Institution or some department of research in a 

 well-equipped university may take hold of the matter and see that the 

 work is thoroughly done. 



Among further printing requirements that are important and that 

 should be insisted on, the letters should have sharp clear-cut outlines, 

 and should be deep black. The paper should be pure white, but with- 

 out gloss, the latter being especially trying to the eyes. According to 

 Cohn and Sack the paper should have a minimum thickness of .075 

 millimeter. Paper of a slightly yellowish tinge is probably not in- 

 jurious and is preferred by Javal. But in general the legibility de- 

 pends on the contrast between the black of the printed forms and the 

 white of their back-ground, and colored or gray papers lessen this 

 difference and thus diminish legibility. Pure white light gives the 

 greatest legibility. The print of one side must not show through from 

 the other, and the printing must be so done that it will not affect the 

 evenness of surface of the other side. 



It is important that wall charts and maps should not contain more 

 names than are absolutely necessary for purposes of instruction, and 

 that these should be in large clear type; or the most important names 

 for reference at a distance and by classes may be in the large type, 

 with the others in type fulfilling the requirements for school-books and 

 for use by individuals at the ordinary reading distance from the 

 chart or map. Burgerstein and Netolitzky advise that school maps 

 should not present the physical and political features on the same 

 map, in the interest of greater legibility. Names printed on colored 

 map surfaces need to be in larger rather than in smaller type than 

 that used in books, if legibility is to be maintained, as any other 

 back-ground than white means diminished legibility. 



The writing upon slates is considerably less legible than that upon 

 good white paper. In the case of blackboards the surface is apt to 

 be gray after erasing, and this, of course, lessens the legibility very 

 considerably. It is important that the blackboard surface be deep 

 black, without gloss from reflection so far as this is possible; and that 

 it be kept clean, avoiding the gray effect. Teachers and pupils should 

 acquire the habit of writing on the blackboard in a large plain hand, 

 as the greater distance at which the writing is read and the usually 

 diminished legibility makes this of importance, and especially in the 

 primary school grades. 



In stating the requirements above, I have had in mind the needs 

 of adult readers and of the older school children. The younger chil- 

 dren must have a type much larger than the minima there stated. 

 The reading of young children has not been sufficiently studied to 



