CHAP. VII. IMPROVEMENT OF THE DIVING-BELL. 219 



yet in effect it is not so ; for the moment the vessel gets 

 within the outer angles of the two return arms or kants, 

 she may be said to be in or out of the harbour, as the 

 case might be. In this way the fullest width of entrance 

 and the smallest space for the admission of swell are 

 ingeniously and effectually secured. 



Whilst occupied on the works of the Eamsgate Har- 

 bour, of which he was appointed engineer in 1807, Mr. 

 Rennie made use of the diving-bell in a manner at once 

 novel and ingenious. It will be remembered that Smeaton 

 had employed this machine in the operations connected 

 with the building of the harbour; 1 but his apparatus 

 being of wood, was exceedingly clumsy, and very 

 limited in its uses. In that state Mr. Rennie found it 

 when he was employed to carry on the extensive re- 

 pairs of 1813. The east pier-head was gradually giving 

 way and falling into the sea at its most advanced and 

 important point. No time was to be lost in setting 

 about its repair ; but from the peculiarly exposed and 

 difficult nature of the situation, this was no easy matter. 

 The depth at the pier-head was from 10 to 16 feet at 

 low water of spring tides ; besides, there was a rise of 

 15 feet at spring and 10 feet at neap tides, with a strong 

 current of from two to three knots an hour setting past 

 it both on the flood and at the ebb. The work was also 

 frequently exposed to a heavy sea, as well as to the risk 

 of vessels striking against it on entering or leaving the 

 harbour. Mr. Rennie' s first intention was to surround the 

 pier-head by a dam ; but the water was too deep and 

 the situation too exposed to admit of this expedient. 

 He then bethought him of employing the diving-bell ; 

 but in its then state he found it of very little use. No 

 other mode of action, however, presenting itself, he turned 

 his attention to its improvement as the only means of 

 getting down to the work, the necessity for repairing 



See Life of Smeaton, p. 69. 



