260 



PBACTICAL PHOTO-MICBOGBAPHY 



so that it really constitutes a properly proportioned truss, 

 being in fact similar in design to a strutted girder. It is made 



FIG. 72. Rosenhain's Metallurgical Microscope. (R. & J. Beck.) 



in girder-section throughout ; the upper portion in front having 

 the body rigidly attached, and the lower front portion having 



