392 THE AMERICAN MONTHLY [Dec. 



of the supporting area at a greater distance from the line of 

 gravity, and do so especially at points where a widening is most 

 needed, viz., at the right and left hand sides of the pillar of ^the 

 instrument. 



Clear as this principle is, we find the modern horseshoe-foot 

 by no means always built in accordance with it. Its width 

 across the pillar is contracted and often left here altogether 

 without supports, which are placed at the extreme ends of the 

 side bars and at a spot behind the pillar. In this manner, resting 

 upon three points, the horseshoe-foot assumes the faulty quali- 

 ties of the tripod just mentioned. 



The accompanying drawing shows the foot of a microscope 

 made by Merz of Munich, 35 years ago. This foot has proved 

 of such superior excellence, that its type, in various sizes, has 

 been substituted for the bases of other stands with the same 

 gratifying results. What in other horseshoe-forms presents a 

 narrow curve expands here (Fig. 6 and 7), to an almost straight 

 comparatively long bar b, which by short turns extends its 

 branches xx parallel to each other, the aperture from branch to 

 branch being equal to the width of the microscope stage. Al- 

 though the shape of this foot suggests rather the form of a 

 pronged bar, than that of a horseshoe, it is plain from the pre- 

 ceding that here not only are the advantages inherent to the 

 horseshoe base fully utilized, but greatly enhanced. The 

 branches, as seen in the drawings represent three-sided prisms 

 X X Fig. 6 and 7, sloping toward the median line of the foot. 

 This particular, in connection with the wide opening of the 

 branches, creates a roomy, well-accessible space beneath the 

 stage, even down to the top of the working table, making con- 

 siderable depression of the stage permissible. The total width 

 of the foot as compared with its length (back-toe not included) 

 is about 7:6. Five leather disks e, embeded in recesses v form 

 the sole of this foot. 



Further attention is drawn to the relation in size of the base 

 to that of the body and especially the stage. In the endeavor 

 to reduce the dimensions of the continental microscope, a point 

 has been reached where overdoing a good thing is partially in 

 sight-partially an accomplished fact. The first relates to the 

 base of the larger stands, the second to that of the smaller ones. 



