52 JOURNAL OF THE [February, 



MISCELLANEA. 



Earliest Observation of Multiple Images. — The earliest 

 observer of the phenomenon of microscopic multiple images, was 

 Leeuwenhoek (1632-1723), the Father of Scientific Microscopy. 

 He used the cornea of the eye of the Dragon-fly. ' When I re- 

 moved,' said he, 'the tunica cornea a little from the focus of the 

 microscope, and placed a lighted candle at a small distance in 

 front, I saw some hundreds of wonderfully minute inverted 

 images of the flame of the candle, and these so distinctly that I 

 could discover the motion or trembling in each of them. Direct- 

 ing my view through the same tunica cornea to the steeple of 

 our new church, I saw the representation of a great number of 

 minute steeples, inverted, and they seemed no larger than the 

 point of a needle seen by the naked eye.' 



The compound microscope, of course, by inverting these in- 

 versions, shows the images erect. Leeuwenhoek's observations 

 and discoveries were all made with the simple microscope. 



Eyes of Tabanus. — Every microscopist has noted the geo- 

 metrical symmetry of the beaded lines formed by the corneules 

 of the compound eyes of insects. To this law of graceful ar- 

 rangement the eyes of Tabanus furnish no exception, notwith- 

 standing the division of the cornea into two distinct regions by 

 the line of demarcation which undulates across it. In the speci- 

 men which, examined in its natural state, by reflected light, 

 guides this description, the facets below the common boundary 

 of the two districts have about one-half the diameter of those 

 above it. The observer would naturally expect to see twice as 

 many vertical, or nearly vertical, rows below as above; to find the 

 upper rows in line with only alternate lower ones ; and to dis- 

 cover the rest of the lower ones intercalated between their more 

 honored fellows. ^ Owing, however, to obliqueness of direction, 

 the rows of the smaller facets appear of the same number with 

 those of the larger, and continuous with them. This appearance 

 is purchased at the cost of a considerable bending of the beaded 

 lines from their direct course, where they cross the boundary ; 

 still, the deflection does not, either mathematically or to the eye, 

 destroy the general symmetry. 



'Such intercalations do, indeed, occur ; but only sparingly. In the specimen ex- 

 amined, only three have been observed. 



