74 MODERN SCIENCE READER 



and it is practically no wider at the bottom than at the top 

 even when cutting very thick metal. The speed of travel 

 of the torch can be made about 8 inches per minute on 

 fairly thick metal, and this makes it compare very favor- 

 ably with hot sawing. 



The composition of the steel or its mechanical treatment 

 does not affect the speed with which the metal is cut, or 

 the amount of gas which is used in the cutting. In fact, 

 there is no variation between the rolled, forged, or cast 

 steels and the soft, hardened, tempered, carbonized or 

 Harveyized steel ; and a nickel chrome, high manganese or 

 high carbon steel cuts as easily as the low carbon steels. 



The complete apparatus for cutting, with one of the 

 mechanical appliances for guiding the torch, is shown in 

 Fig. 3. The two steel bottles at the right of the picture 

 contain the oxygen and hydrogen which is stored under a 

 pressure of from 1,500 to 2,000 pounds per square inch. 



Each bottle is provided with a needle valve to which is 

 attached a pressure regulator governing the flow, so that 

 the gas will be delivered to the mixer and from thence to 

 the torch at a constant pressure. A high-pressure gage is 

 located between the needle valve and pressure regulator in 

 order to show at all times the contents of the tank and to 

 determine the amount of gas consumed in any cutting 

 operation. A low-pressure gage is also attached to the 

 regulator showing the pressure of gas as used' for cutting. 

 The cutting pressure can thus be varied to suit the char- 

 acter of the work by turning a thumb screw on the regu- 

 lator. From the regulator the gas is conducted by heavily 

 armored tubing to the mixer. 



The mixer is shown on the floor beside the bottles and 

 the gases are conducted through it by a conical worm- 

 shaped pipe made of thin metal, this pipe being surrounded 

 by cool water as a safety provision against explosion of the 

 mixed gases. 



In Fig. 3 the torch rides on a frame that is provided 

 with two ways for guiding it in a straight line. 



