Achievements of Electron Microscopy 



93 



The most important recent addition to electron microscope 

 techniques is the shadozvcast method, chiefly connected with the 

 names of Wilhams and Wyckoff.^"* It appears that it occurred 

 to Miiller first to show up fine details of surfaces by coating 

 them partially with a thin layer of silver, condensed in high 

 vacuum from a collimated atomic beam, at almost grazing in- 

 cidence to the surface. Every minute projection on the surface, 

 facing toward the beam will be coated, whereas parts facing the 

 opposite way remain clear. But silver has a strong tendency to 

 aggregate in specks, therefore Miiller's attempts were only mod- 

 erately successful. Williams and Wyckoff in a careful study 



Fig. 34b. "Caryophanon" 



