With a lens of such a focal length we shall require a camera with very long bellows to obtain much magnification of our object but, if our camera is one with only short bellows, we can still overcome our difficulties. If the extra expense is no object we can obtain one of the excellent Aldis lenses of only two inches focal length, especially designed for this work; if we are ingenious we can construct a device which will answer our purpose admirably and cost but a few pence. With the simple apparatus we are about to describe photo-micrographs up to ten diameters magnification can be obtained in most cameras. The term, ten diameters, may appear puzzling but really it is quite simple. Suppose we wish to make a photo-micrograph of a penny stamp and we wish it to be magnified ten diameters, we should require a large camera for the operation, but that, for the moment, is beside the point. Our penny stamp, magnified ten diameters, would be equal in area to ten horizontal rows of stamps, each row containing ten stamps or, in other words, it would occupy the same area as one hundred penny stamps. To find the magnification possible with our camera and lens, extend the camera bellows to the full and set up a foot rule in front of the lens. Move the camera from a distance slowly towards the rule till it is sharply focussed, then carefully measure the distance between the inch lines on the focussing screen; if the lines are three inches apart we shall be able to make photo-micrographs three times the size of our object and we shall probably desire something better.