Becker — A Netv Principle in Blowpipe Construction. 277 



the operation of changing the jets could be " codified " so as to be performed 

 mechanically, obviously the effect would be quite as good as an air-jet of 

 variable bore. 



Consideration of the possible ways in which this might be accomplished 

 directed attention to the tubular shape, which is invariably seen in all types 

 of blowpipe, and it was quickly realized tliat this shape, if retained, would 

 render the design of a compact blowpipe, such as was contemplated, extremely 

 difficult, if not impossible. 



At first it was thought tliat the persistence of this shape in all types of 

 blowpipe was due to the fact that it was necessary for the proper functioning 

 of the blowpipe ; but a few experiments soon showed that the tubular shape 

 liad little or no effect on the shape of the flame, and was by no means an 

 essential feature of the blowpipe. The persistence of this shape, which only 

 tends to make the blowpipes more unwieldy and awkward than they other- 

 wise would be, appears to be due to the fact that the original blowpipe was 

 made in this form, and later designers have merely modified it, without 

 attempting any radical departure. 



It was therefore decided to abandon this tubular form altogether in the 

 design of the blowpipe to be described in this paper, and to keep the gas 

 chamber as compact as possible, as it had been shown that this could be done 

 without sacrificing efficiency in any way. By doing so it was found com- 

 paratively easy to design a blowpipe fulfilling the conditions which were 

 deemed essential. 



The objects aimed at in the design to be described are : — 



1. To enable the change from one flame to another to be made with the 

 minimum of attention. 



2. To vary the air-supply by means of jets of different bore, the air- 

 pressure being constant. 



3. To vary the gas supply simultaneously with the air. 



4. To enable any air-jet to be used with any given size of flame, in order 

 to vary the character of the flame. 



5. To make provision for a flat flame. 



6. To keep the whole as compact as possible. 



The principle on which the instrument is based consists in placing a 

 number of small gas chambers (each provided with an air-jet of different 

 bore) round the periphery of a cylinder, mounted on a horizontal axis, 

 throiigh which gas and air are supplied in such a way that any size of flame 

 can be brought into operation by mere rotation of the cylinder. 



