OKLAHOMA ACADEMY OF SCIENCE 131 



of sufficiently large opening the radiation loss predominates over 

 the loss at the vertex. In this case, in the steady state of vibration, 

 when the energy input equals the output, the energy input has a 

 constant value independent of the size of the opening of the horn. 

 Thus the amplification or the energy input per unit area of the 

 opening is inversely proportional to the area of the opening. 



Thus the two energy losses (1) by abstraction at the vertex 

 and (2) by radiation from the opening of the horn tend to respec- 

 tively increase and decrease the amplification as the opening of the 

 horn is increased. The former loss predominates for horns of 

 sm.all opening and the latter for horns of large opening. Hence 

 when both losses are operative, there must be an optimum angle 

 of greatest amplication. Mathematical analysis shows thit at this 

 angle the energy loss at the open end equals that from the vertex. 



XXIX. A ELECTROMETER FOR MEASURING THE 



RABIOACTIVITY OF G/SES FROM OIL AND 



GAS WELLS 



F. K. Harris 



From the Phy^icj Laborstcry of the Un'veTS'ty of Oklah-^ma 



The ultimate purpose of the problem is to determine whether 

 or not the Helium-bearing earth gases have any radioactivity and to 

 determine the amount of radioactive content of the gases. 



It is a v/ell known fact that the gases from many oil and 

 gas fie'ds have an appreciable helium content. This is in it:elf 

 strong evidence of their radioactivity but cannot at present be 

 accepted as conc-usive proof. There has been some work done 

 along this line in the past year or so but is as yet unpublished. This 

 Avork is being carried out by an oil company operating in Texas. I 

 have, up to the present, been unable to get any information as to 

 the methods thev are using and the results obtained. I presume, 

 however, that the gas is collected ani its activity measured in 

 some '^ort of emanation chamber. 



The electrom.eter here described is designed to measure the 

 radioactivity of flowing gas. The order of the effect expected 

 is so small that the instrument used must be of high sensitivity. 

 Portability and compactness are also of prime importance. The 

 instrument therefore selected is an electroscope of low capacity. 

 The electroscope head of the Lind Interchangeable Electroscope is 

 used as a leaf system (this is described fully in Bulletin No. 176 

 Denver Fire Clay Company). The leaf system is incased in a 

 metal cvlinder 10cm. in diameter by 6cra. long. It is suspended 



