JOURNAL OF MICROSCOPICAL SCIENCE. 



EXPLANATION OF PLATE IV. 



Illustrating Mr. Gorham's paper on the Magnifying Power 

 of Short Spaces. 



In the third horizontal column the single aperture which is held at tJie 

 distal end of the instrument is shown in four of its phases of revolution. 



In the fourth horizontal column, is delineated one of the objects (equi- 

 lateral triangle) chosen for examination, and placed close in front of the 

 eye in the circular end of the instrument. 



Tlie first, second, and fifth horizontal columns show in their uncom- 

 bincd state the planes which are formed by the mutual intersection of the 

 two upper series. Thus the lines one and five contribute to the produc- 

 tion of the planes nine, thirteen, and seventeen : the lines two and six to 

 the planes ten, fourteen, and eighteen, and so on. 



In the lowermost colunm is shown the coalescence of these planes into 

 one entire form, tlie triangular prism, i)resenting itself in four different 

 aspects, in accordance with the inclination of the lines 1, 2, 3, and 4, in 

 the uppermost scries. 



