1036 TUBES 



however, never produced good taper tubes. ' An after invention consisted in using a 

 pair of rolls with diminishing grooves on their diameter or circumference, and 

 presenting the taper mandril with its sheath of metal at its smallest diameter to the 

 narrowest part of the groove ; the revolution or partial revolution of the rolls com- 

 pressed the metal sheath to the mandril and produced a taper, but still irregular 

 taper tube. This method was patented by Henry Osburn so far back as the year 

 1813. It, however, seems to have been lost sight of, from the limited demand for 

 taper tubes at the period, and the same process was revived by Church and Harlow in 

 1841. Though great numbers of taper tubes so made are still produced, it is obvious 

 that, from the very nature of the action of the rolls, the production of taper tubes is 

 limited to those of a purely tapering, externally smooth cylinder ; and it would be 

 impossible to produce either reeded, fluted, or twisted tapering tubes by the rolling 

 process. The means, however, by which nearly every variety of tapering tubes can 

 be produced, was effected in 1850 by John Ward, who in that year suggested, instead 

 of an expanding tool made up of a complication of segments of steel, operated upon 

 by springs, or that of the rolling process as already described (see fig. 2056), the pro- 

 . - . duction of a tool, draw-plate, or die formed in one piece, and of 



block tin cast in a metal mould. This tool, placed in the posi- 

 tion of a 'die' in the drawbench, by the expanding yet com- 

 pressing property of the metal of which it is made, forces the 

 metal of the sheath to be converted into a taper tube, and into 

 every groove or reed in the internal mandril or support on 

 which the sheath or case to form the taper tube is placed. By the 

 same process, also, tapering tubes with convex or concave twist- 

 ings, threads, or reeds on the outer diameter can also be produced by the application 

 of a swivel on the drawbench chain, which permits the mandril and its case of metal 

 to revolve in its passage through the tool, the tool remaining stationary. The process 

 may be described as follows : The die or mould to produce the block-tin tool is formed 

 of metal ; the aperture in its centre is tapering cylindrical if for a plain round 

 taper tube or if reeded, fluted, or twisted, a metal core with its requisite reeds, flutes, 

 threads, or twists is introduced into the centre of the mould, and the tin poured in : 

 the result is a cast, the interior of which is a copy of the mandril, and also of the 

 external contour of the desired tube. Fig. 2057 shows external appearance of the tool 

 when cast, and fig. 2058 its internal configuration, depending on the plain or orna- 



2057 2058 2059 



mental character of the tube. The sheet brass or iron, being cut to the required 

 diminishing breadth, is turned up and soldered at the joint, after the removal of the 

 wires which held the edges of the partially-formed tube, together, and the extra solder, 

 the case to form the intended taper tube, &c., is placed on the mandril. In Fit/. 2059, 

 A A represents the sheath of brass to form the taper tube ; B B, the mandril ; the tool 

 is then placed in the proper position in the drawbench, the end of the mandril forced 

 through it, and taken hold of by the ptyers attached to the chain ; the tool expands 

 and compresses the sheath against the internal mandril, clinging, yet expanding 

 with the increased diameter of the taper of the tube and mandril it is drawn 

 through. The result is a perfectly-formed taper tube, a perfect copy externally of 

 the mandril on which the tube is placed. If the mandril is of an ornamental spira 1 

 construction, provision is made, as has been already stated, to admit of a screw-like 

 revolution to indent the metal case into the concavities or threads cut on it externally, 

 i.e., the tool representing a stationary nut, and the mandril and its covering a screw 

 in motion. 



Finish of Cased and other Brass Tubes. As regards the mode of finish adopted for 

 tubes of which immense quantities are sent out in long lengths, especially of the iron 

 cased with brass variety, it has been the custom of the trade to finish such by means 

 of hand-labour only ; the artizan engaged in the process using ' floats,' or files cut 

 in one direction only, for the purpose of the removal of the external skin preparatory 

 to polishing. One house only has applied or substituted a machine for the purpose 

 of finishing tube. i.e. that of W. Tonks and Sons, Birmingham, Their machine 

 is self-acting. The tube to bo floated is attached to a horizontal bed : the floats, 

 five in number, move parallel, and in a longitudinal direction. Each in its operation 

 passes a little into the space previously floated ; the tube is turned by the machine, 



