1886.] on Properties common to Fluids and Solid Metals. 403 



with the aid of skilful artificers in the Mint, the few specimens I 

 have to submit to you. I allude to the metal work in banded 

 alloys to which the Japanese give the name of Moku-me, or " wood- 

 grain." In its preparation thin layers of coj)per, precious metals, 

 and various alloys, are soldered in superposition like the leaves of a 

 book ; through these layers, as is shown in Fig. 9, holes are drilled 



Fig. 9. 



to varying depths in the thickuusw ui tuu mcLtii, ur utiuches are 

 cut in it. The mass is then hammered flat until the hole or trenches 

 disapx^ear, and the result is contorted bands, of some complexity, 

 and often possessing much beauty, especially when the colour of 

 the metal is developed by suitable chemical treatment and polishing. 

 A similar effect may be produced by beating up the metal from one 

 side, and filing the other flat, as is shown in Fig 10. The structure 

 depends on the flow of the respective metals of which the mass is 

 composed, and behaviour of the components of the system, and 

 suggests one of the most marked facts in experimental hydrodyna- 

 mics, namely, the difference in the way in which water flows along 

 contracting and expanding channels. The sinuous lines the metal 

 assumes in the preparation of Moku-me, resemble the beautiful illus- 

 trations devised by Professor Osborne Eeynolds, to show the flow of 

 water. 



We have hitherto only considered the flow of metals when sub- 

 mitted to compression, let us now examine the effect of traction. 

 When a viscous metal, such as iron or soft steel, is submitted to stress 

 by pulling its ends in oi>posite directious, it stretches uniformly 



