The narrow slot shown in figure 1 will eventually be 

 the front of the gap. Note how the gap space widens toward 

 the rear. Although the picture shows one continuous piece 

 of brass, the metal will eventually be machined, after 

 encapsulating in a suitable dielectric material, into two 

 separate halves. This is an original technique, which 

 insures a constant gap spacing. Many configurations have 

 been tried and all incorporate the principle of having the 

 narrowest part of the gap at the front to prevent the discharge 

 from occurring insi de the material where it will not only 

 be ineffective but will explode the gap. Figure 2 shows 

 several types of underwater spark gaps investigated. 



Figure 2. Variety of underwater spark gaps investigated. 



