366 MOTIONS OF INSECTS. 



the most ignorant and stupid of his domestics, were 

 never satisfied with looking at it. Never had any armil- 

 lary sphere so many zones, as there were here circles, 

 which had the light for their centre. There was an in- 

 finity of them crossing each other in all directions, and 

 of every imaginable inclination all of which were more 

 or less eccentric. Each zone was composed of an un- 

 broken string of Ephemera?, resembling a piece of silver 

 lace formed into a circle deeply notched, and consisting 

 of equal triangles placed end to end (so that one of the 

 angles of that which followed touched the middle of the 

 base of that which preceded), and moving with asto- 

 nishing rapidity. The wings of the flies, which was all 

 of them that could then be distinguished, formed this 

 appearance. Each of these creatures, after having de- 

 scribed one or two orbits, fell upon the earth or into the 

 water, but not in consequence of being burned a . Reau- 

 mur was one of the most accurate of observers ; and yet 

 I suspect that the appearance he describes was a visual 

 deception, and for the following reason. I was once 

 walking in the day-time with a friend b , when our at- 

 tention was caught by myriads of small flies, which were 

 dancing under every tree ; viewed in a certain light 

 they appeared a concatenated series of insects (as Reau- 

 mur has here described his Ephemerae) moving in a 

 spiral direction upwards ; but each series upon close 

 examination, we found was produced by the asto- 

 nishingly rapid movement of a single fly. Indeed, when 



a Reaum. vi. 484. t. xlv./. 7. 



' b The persons observing the appearance here related were the 

 authors of this work. 



