Magnification - amended paragraph

Since the lenses in the microscope are rotated to adjust focus and rotation of the objective lenses does not alter the size of the object on the screen, magnification of the image we see is by our eye (ie, because focal length is reduced) and from a magnifying lens within the microscope, or possibly projection from below, depending on how the microscope is lit internally.  In fact, the magnified cylinder looks, on inspection, likely to be only that of the focal adjustment itself, so that we are most likely to be seeing an image of the lens object magnified by a lens higher up the microscope, since this would allow the greatest magnification, or we may be viewing a projected image of the object as it is magnified and reflected lower down the microscope.  On the other hand, a cylinder will have the effect of making something beyond our focal range come into focus (just as it will amplify sound), so that at least some of the magnification, or clarification, will be due to the cylinder alone.  That magnification is relatively low seems likely given the similarity in appearance of the image of our own lens and the image on the ‘screen’ within the microscope, such that our eye, or a lens within the microscope, or a mirror within the microscope, or the cylinder alone is magnifying and clarifying an object with a similar but smaller structure or, more likely, is magnifying and clarifying a smaller object with similarly sized parts. 

 

In sum, we are at most seeing only a blurred impression of part of the material on the glass slide, and probably its stain, and the clear and detailed object one sees when looking into a microscope is likely to be of the lens of a small bird’s eye contained within the microscope at a relatively low magnification, including that done by our eye and the cylinder of the lens tube, in addition to the moving and more translucent image of the lens, or lenses, of our own eye above it.