as the current to the electro-magnet is cut. Here, once more, a failure 

 of electric current would not be catastrophic, although it would lead to 

 the loss of the tubs and the magnetic valves. The bathyscaphe would 

 go up again at full speed, but without the occupants being exposed 

 to the slightest risk. 



Fig. 1 8 explains the apparatus which, on deck, holds the chain: 

 its last link, of a special form, is hooked to the extremity E of the small 

 arm of the lever EACD. It cannot slide towards the left and release 

 itself because the fixed hook J stops it from escaping. The lever is held 



Fig. 1 8. Diagram of lever supporting the ballast tub 



by the electro-magnet M. As soon as this magnet lets go, the lever 

 pivots around its axis A and the chain is released. 



Upon the surface we can, in order to economize the electric current, 

 lock the lever either by means of a pin B or by means of the turn- 

 buckle H. The reason for this double locking is that if it is the pin which 

 retains the lever and if the electro-magnet does not work, the whole 

 right arm of the lever is entirely unloaded. 



On the other hand, if the turnbuckle is brought into action and the 

 pin is removed, then the lever is subjected to the effect of the load and 

 deflects slightly. The left extremity of the arm FG then moves away 

 slightly from the lever. This movement can be easily measured by 

 means of a little graduated wedge. Since the elastic deformation of the 

 lever is proportionate to its load, our lever plays the part of a dynamo- 

 meter. It thus permits us to measure the quantity of ballast which is 



[ 156] 



