356 Objects Viewed through the Cornea of the Insect Eye. 



OBJECTS VIEWED THEOUGH THE COENEA OF 

 THE INSECT EYE. 



BY THOMAS PEINCE. 



Miceoscopists are aware of the usual method of proving that 

 the compound cornea of the eyes of insects are composed of 

 numerous lenses, merely by placing beneath the stage, and 

 behind the mounted cornea, any strongly denned object, a 

 candle, a knife point, etc. A really interesting and beautiful 

 arrangement, adapted for a soiree or public exhibition, may be 

 made as follows : — 



a, Fig. 1, represents the lamp flame; &, a three-inch 

 bull's-eye condenser, so placed in relation to the lamp as to 



Fig. 1. 



produce parallel rays ; c, a photograph on glass, known as a 

 " transparent positive/' this in my case represents a por- 

 trait of Shakspeare — it is three inches diameter, and placed 

 near the bull's-eye ; d, an achromatic condenser ; e, stage of 

 microscope, distant about ten inches from c, the photo- 

 graph; f, an ordinary slide -of the cornea of an insect's eye, 

 known among microscopists as one " mounted to show the 

 image"; g, shows the point where the image is formed, a 

 little in front of the cornea ; as the picture will not be seen 

 when the facets of the eye are in focus ; h represents a quarter- 

 inch objective, supposed to be in its ordinary position in the 

 body of the microscope. 



In adjusting the focus to find the image, it is desirable to 

 work the rackworks of the body and the condenser at the same 

 time, as the slightest movement of one affects the focus of the 

 other. The apparatus described above, if carefully centred 

 with the body of the instrument, will produce a novel and 

 pleasing result, showing as many distinct portraits as there 



