154 Micro-ruling on Glass and Steel. 



were formed by the fan-spokes of the primary having the shape 

 shown in Fig. 3, where each secondary spoke shows a knife edge near 

 its outer margin, which thickens when the intersections begin, and 

 broadens towards the centre of the disk. The transverse or nearly 

 concentric markings arising from intersections are more striking 

 than in the glass star, and exhibit an iridescence differing from that 

 of adjacent parts. 



The primary and secondary stars are easily made to look semi- 

 transparent, as if those parts where the lines are thickest were com- 

 posed of extremely fine silver gauze. 



The most remarkable work which I have seen of Mr. Stanistreet's, 

 is a star on steel, about half an inch in diameter, displaying 10 rays, 

 each consisting of 12* bands of 40 lines each, making 4800 lines. 

 Each ray has what Mr. Stanistreet calls a " serried edge " (as shown 

 in Fig. 4), caused by the diamond point commencing each stroke a 

 very little nearer to the centre, and so on in each band of 40 parallel 

 lines. Then the next band of 40 hnes is commenced at an angle of 

 1° 26' 24" from the preceding band, and ruled in like manner 

 towards the centre of the star, and so in each of the twelve bands 

 which constitute one ray of the star. These bands oi parallel lines, 

 by their mutual intersection at the above angle, give the wavy, or 

 watered-silk pattern crossing each stellar ray, of which there are 10. 

 In addition to the lines of the highly complex rays, there are groups 

 of radial lines between each pair of rays, 250 in all. These radial 

 lines, added to the 4800 parallel lines, make a total of 5050 lines in 

 the whole pattern. The highly complex character of this star, the 

 closeness of the lines composing the bands, and the very numerous 

 intersections, give rise to very remarkable optical effects. Lit up 

 with a silver reflector, the bands all stand up more or less vertically ; 

 the upper surface of these bands, or what seems such, is exquisitely 

 watered when seen with a 3-inch objective, and the transverse bands 

 produced at recurring distances by multitudinous intersections, look 

 irregularly raised above the general surface, and the whole seems a 

 fine tissue of glass threads, more or less iridescent. The secondary 

 star produced by intersection is very striking in this specimen, 

 and where two secondary rays intersect, a tertiary one will be seen. 

 If a group of the radial lines is observed near the circumference of 

 the star, they all look in one horizontal plane ; but where they inter- 

 sect the lines of the bands they look above or below, according to 

 position and angle of illumination. 



With a power of frds and the useful vertical illuminator devised 

 by the late Joseph Beck, the view which best satisfies the eye repre- 

 sents the lines as solid threads one under the other when simple, 

 intersection takes place, and a tendency is created to view the spots of 

 complicated intersection as higher than the rest. With a power of ;jth 



* By acoiflent the engraver has made IS bands instead of 12. 



