GUN EEPOET NOISE i— ACTION OF THE MAXIM SI- 

 LENCER AND THE DIFFERENCE BETWEEN REPORT 

 NOISE AND BULLET-FLIGHT NOISE EXPLAINED. 



By HiKAM Percy Maxim. 



[With 7 plates.] 



When a gim is discharged it is the common idea that there is a 

 single noise heard — the report noise. That such is not the case, and 

 that there are two entirely separate and distinct noises has been 

 proved in a very interesting manner by the advent of the Maxim 

 silencer. The history of the research work which led np to this 

 device is very instructive and well worth recording. 



Wlien the work was undertaken, at the beginning the object was 

 to annul report noise so that concealment of position, partly attained 

 by smokeless powder, would be completed. When the firing line be- 

 came invisible there was only left the report noise to indicate its 

 position and also its strength or number of guns. 



To attain this object, it was thought only necessary to check the 

 suddemiess of the release of the high pressure powder gases into the 

 atmosphere. This pressure, in the caliber 30 United States service 

 Springfield rifle, wag approximately 10,000 pounds per square inch, 

 when the base of the bullet emerged from the barrel muzzle. A de- 

 vice must be found which would present an unobstructed path for the 

 bullet, but this path must not be available to the gas, at least easily. 



The search for a path which would give a bullet an absolutely un- 

 impaired passage, and yet would check gas at 10,000 pounds pressure 

 per square inch, was a long one. For a year it persisted without 

 results. Its successful ending came in a very interesting though 

 extremely prosaic manner. The essential element was a hole which 

 would be pervious to a rifle bullet but impervious to high-pressure 

 gas. One morning, after taking a bath and pulling the plug in the 

 tub drain hole, the water was given an accidental twist and the 



1 Reprinted by permission from Science Conspectus, vol. 6, No. 2, 1916. 



193 



