47& 



DISCOVERY REPORTS 



N. Rear propeller guard and lifting handle, secured at the top along with M to J and below to C 



/"T7* \ 



O. Propeller shaft bearing of lignum vitae or special anti-friction metal (Tenaxus Ai Plastic 



metal) (Figs. 3). 



P. The propeller (see Fig. 6) consists of three blades each z| in. long from boss to tip and i ¥ in. 

 wide at widest part. These are set in a cast central boss and each secured in position by a screw. 



X3ZT 



INCHES 

 O I 2 



I ■ ■ ■ t - ■ - 1 .1.1.1 



TXT 



L 



LlL 



Fig. 5. Scale drawing of the Type II Recorder seen from in front with part of the towing eye D removed to 

 show the details of the vertical fin assembly hehind. The internal details of the forward casting A and 

 the internal mechanism frame are shown in broken line. For letter references see text. 



By means of these screws they may be fixed at any desired angle, so that the pitch of the blades 

 may be altered to give varying speeds of revolution in relation to the passing water, and thus a 

 varying speed of winding to the gauze bandings in the internal mechanism. Each section on the 

 gauze may therefore be made to represent one or more miles of sea traversed as desired. 1 A 

 numbered scale is provided on the boss against each blade, so that each may be correctly adjusted 

 by bringing an engraved line on the blade opposite a particular point on the adjacent scale. The 

 boss is drilled to slide on to the propeller shaft to which it is secured by two set screws. The tail 

 end of the propeller shaft is drilled to take a split pin which is inserted as a safety measure. 



1 Seep. 495. 



