182 MATTHEW FONTAINE MAURY 



or group of torpedoes. When either operator observes 

 an enemy in range with any torpedo, he closes his circuit 

 for that torpedo. If the enemy before getting out of 

 this range should enter the range for any torpedo from 

 the other station, the operator there closes his circuit 

 and discharges the igniting spark. Consequently, if the 

 ranges belong to the same torpedo, its explosion takes 

 place. But if not, there will be no explosion. Hence, 

 here is an artifice by which explosion becomes impossible 

 when the enemy is not in the field of destruction and sure 

 when she is. 2. The Electrical Gauge, a contrivance of 

 my own which you perfectly understand and some of 

 which you have already made ; by means of it one of the 

 tests which the igniting fuse has to undergo before it is 

 accepted is applied. By means of it, the operators can 

 telegraph through the fuse to each other without risk to 

 the torpedoes and by which the torpedoes may without 

 detriment to their explosibility be tested daily or as often 

 as required. And thus the operators can at all times 

 make sure that all is right. 3. A plan for planting tor- 

 pedoes where the water is too deep for them to lie on the 

 bottom and explode with effect, by which they will not 

 interfere with the navigation of the channels and by 

 which, when the enemy makes his appearance, they 

 may by the touch of a key be brought instantly into the 

 required position at the required depth. These con- 

 trivances are very simple. They are readily understood 

 from verbal description. They require neither models 

 nor drawings for illustration. You understand them 

 all. They are of little or no value except to governments 

 and, as against these letters of patent are of no use, I 

 have not deemed letters patent desirable. I have every 



