208 MICROSCOPIC OBJECTS. 



rent objects may be viewed with the low powers of the 

 Megaloscope (without producing any sensible optical 

 deception) by the light of the sun as modified by passing 

 through the denser part of the atmosphere in contract 

 with the earth, when the disc is perhaps only 20"^ high 

 above the horizon, or thereabouts ; and it would be a 

 great pity if they could not, for still more beautiful are 

 those leaves, and those blades of grass, and those rich 

 mosses, and the petals of those wild flowers, when viewed 

 by the Megaloscope than by the naked eye, and still more 

 dehght do they occasion to the senses of the observer. 

 Nothing is more simple than the mode of managing 

 the Megaloscope with this simple illumination. We 

 have only to mount it horizontally, and then tilt it, till 

 the sun's light falls at the required angle on the object, 

 and to place a needle equipped with a disc of black velvet 

 stuck on cork, large enough to form a ground to the whole 

 field of view, at a little distance behind the body under 

 examination, but of course so posited as not to intercept 

 the oblique rays of the sun. If some such arrangement 

 is not made, the field may chance not to be black, but of 

 some other colour — green, for example, if there is a 

 green field between your instrument and the sun ; in fact 

 you may make the ground of what colour you like by 

 using coloured discs; a bright cobalt blue makes, I 

 think, a beautiftd ground for green objects, and green for 

 red or crimson ones, &c. 



As the light of the sun is not always to be had, I 

 have attempted to modify the natural light of that body 



