CONSTRUCTION OF THE WIRE FRAMES. 29 



of the wire is also brought into contact with it, and when a firm 

 adhesion is obtained, the ring is removed from the flame and 

 allowed to cool, the parts being kept in the proper position until the 

 solder becomes solid. Finally, the soldering water which may 

 have remained is removed by washing. As the whole ring becomes 

 very hot during the operation, the straight handle of it should be 

 placed between flat pliers and held in the left hand, leaving the 

 right hand free for the soldering and directing the free end of the 

 wire with the flat tweezers. 



The frame, fig. 27, is made thus. A piece of wire, about 36 cm 

 long, is first somewhat straightened with the fingers and flat pliers, 

 and then divided, by compasses or measuring rule, into 6 equal 

 parts, the divisions being marked by a slight scratch with a three- 

 cornered file ; if the scratch is made deep, the wire will break if 

 bent at that place afterwards. The first part, one sixth of the whole 

 length,- forms the handle ae ; at a the wire is slightly bent, the 

 second point of division forms then the angle at ft, the third at c, 

 and the fourth returns to a, abc forming an equilateral triangle. At 

 a the wire is again bent downwards, the fifth division being placed 

 at d, and the end at &. The whole is now adjusted until the dis- 

 tance between c and d is nearly equal to the length of the other 

 sides, a&, &c, etc., and the corners are now soldered together, first a, 

 then 6. Finally, a single piece of wire of the proper length is 

 soldered to c and d. 



The cubical frame, fig. 28, A, requires a piece of wire 60 cm long, 

 divided into 10 equal parts. The first of these forms the handle, 

 the four next supply the sides gh, he, ef\ fg ; the sixth forms the 

 side yc, and the square cdab is formed by the remaining four parts, 

 the end of the wire thus returning to c. Solder first at a, then at c, 

 and insert finally three single pieces each 6 cm long for the sides hd t 

 ea, and/6* 



The ring with the legs is shaped like the other rings, but the pro- 

 jecting piece is made shorter and forms one of the legs ; to supply 

 the other legs two pieces of equal length with it are soldered to 

 the ring separately. 



Iron does not take solder so well as brass ; but if the iron wire 

 is very bright, or polished with emery-powder, the frames may be 

 easily made of iron wire, with a little patience.. 



5. Porosity. -Many bodies, for instance a piece of 

 sponge, pumicestone, bread, etc.,' do not fill space com- 

 pletely, but between the particles of matter of which 



