April — sept. 1859.] Proceedings. 



183 



cup-shaped depression. They are arranged in rows, but the 

 scales composing the row are not uniformly placed. In some 

 Butterflies, each scale overlaps its neighbour by nearly half of its 

 width, like the petals of many flowers. In others the scales are 

 placed side by side without overlapping, but the points of junc- 

 ture in one row are made to fall upon the middle of the scales of 

 the row beneath. But in either case the several rows overlap each 

 other as slates are made to do on a roof. 



A well selected Butterfly's wing is a surpassingly beautiful ob- 

 ject when viewed with a moderate power by reflected light, and 

 never fails to call forth the admiration of the beholder. The 

 scales have long been favorite objects with the Microscopist, and 

 the resolution of the ultimate structure of some of them is still 

 among the most difficult feats, the microscope is called upon to 

 assist in. In structure they very much resemble the wing, con- 

 sisting of an exceedingly delicate framework, and two (some say 

 three) membranes. The scale represented by the photograph is 

 from a small species of Thecla, which are many of them beauti- 

 fully marked, and may be found in great numbers in the cold sea- 

 son of the year. They fly low, and are easily captured in the 

 morning before sunrise, at which hour they will be found on grass 

 or low shrubs. 



When this scale is examined with a sufficiently high power 

 (from 1,500 to 2,000 diameters) it very much resembles an old 

 fashioned window, the delicate framework enclosing a number of 

 hexagonal areolae, the two opposite sides which form the trans- 

 verse striae of the scale, being much longer than the other four 

 sides of the hexagon. 



To those who have not seen the minute works of the Creator, as 

 displayed by the beautiful microscopes of the present day ; it must 

 seem like jesting to talk of the framework of an atom, the sur- 

 face of which measures only g^ J-^th of a superficial inch, and 

 which is quite invisible to unassisted vision, there is, however, 

 sufficient indication in the photograph of its existence, although 

 the power used was only equal to 520 diameters. But these mi- 

 nute hexagonal spaces admit of accurate measurement with a 

 screw Micrometer, and I find that it would require 311, 681, 510 



