﻿78 ,Mr. W. B. Croft: Some 



35. Three equilateral triangles with a small triangular area 

 at the common centre. 



41. Ten semicircles near to one another and parallel : the 

 feature of this is the broken shaggy brushes at the ends of the 

 semicircles. 



43, 44, 45. A parabola lying within another one of smaller 

 parameter ; the lines of light being rather thicker about the 

 vertices. In 44 each vertex has opened, turned the broken 

 edge back and taken a small ball into the open mouth : the 

 bands about the axis, which is not drawn in the original, are 

 diffraction creations : the inner parabola is broken into flakes 

 about the vertex by dark cross lines. 



42. An hyperbola and its conjugate, twice repeated, without 

 asymptotes. The flaking appearance is noticeable. 



46. Two ellipses, side by side : as a larger circle gives a 

 smaller central spot, the curve at the end of the minor axes 

 gives a smaller spot, and that at the end of the major ones a 

 larger spot : the result is the broadening white line in the 

 figure. 



47. Five diminishing circles with internal contact, w 7 here 

 the lines are made thinner : here are the shaggy offshoots 

 similar to those in 41. 



50. Three circles, near, not quite touching. Arago spots 

 and flaking. 



48. 49, 51. Arago spots made by small arcs of circles. 



52. A square divided into 4 small squares, in each of these 

 a circle inscribed, not quite touching. Not to mention the 

 small detail, this figure suffers the curious inversion of ap- 

 pearing as 4 circles with inscribed squares. 



53. Four circles. 



54. A square with an external semicircle on each side. 



55. Five small circles in a ring touching one another. 



56. Two circles, each through the centre of the other. 



57. Two unequal circles, near, not quite touching : the 

 larger spot in the smaller circle, and the flaking disturbance 

 of the larger by the neighbourhood of the smaller. 



60, 66. Eight small circles in a ring touching one another: 

 in each case there is the bright spot at the centre of each 

 circle, in 66 there is one at the centre of the whole figure : 

 the formation of the common tangents at the points of con- 

 tact is not difficult to imagine. 



58. 59. The square and triangle which have turned about 

 and point inwards : their sides have been resolved entirely 

 into transverse flakes. 



62. A square with thicker fines of light. 



