10 Description of a New Tow-Net 



conditions of sea and weather when no tow-net could be guaranteed 

 to act with satisfaction. On one occasion, at the end of a long cruise 

 (in 1903), one of the side-springs broke, but this was easily replaced 

 on board, and once, in 1904, when the net unfortunately had been 

 bumping against the floor of the sea, the central piston became bent, 

 and the weakening thus caused led to its breakage shortly afterwards. 

 This, however, was quickly repaired on board. The net is designed 

 to tow horizontally. As will be seen from the figure, it consists of 

 four detachable pieces : (1) The main cylinder, with arrangement at 

 the bottom for attaching weight, if necessary, and thermometers- 

 (2) Sliding down it a central piston which rims freely through the top 

 piece, enlarged at the bottom end that it may, when full}' withdrawn, 

 catch upon the side-springs inserted inside the upper portion of the 

 main cylinder ; these springs are then pushed through the lateral slots, 

 and are designed to catch the arms of the net-frame and hold the 

 lower pair in position when the net is closed ready for lowering. The 

 upper portion of the central cylinder (detachable with the piston) has 

 strong lateral steel springs (we have found steel preferable to any 

 other metal for this purpose, and with proper attention it does not 

 rust), four in number. (3) A funnel-shaped top piece put on over the 

 top springs, and which receives the impact of the large closing 

 messenger. (4) The four arms of the net-frame, attached to short 

 metal tubes which slide freely over the main cylinder. 



When the net is about to be used, the wire is run through the 

 piston and main cylinder and bent on to the device at the bottom (this 

 is cast in one piece with the main cylinder) ; the top piece is screwed 

 home on the main cylinder, the funnel pushed slightly down, the arms 

 raised, and the piston drawn up, so that the lower pair of arms catch 

 on the smaller pair of side-springs in the main cylinder, which is 

 insured by raising the piston. By pushing down the funnel the upper 

 arms are caught on the four strong springs of the top piece, and they 

 are made secure by withdrawing the funnel a little. The net is then 

 ready, securely closed, for lowering. To open it under water, a small 

 messenger is sent down which strikes the top of the piston, drives it 

 down the cylinder, the lateral springs of which recede inside, and the 



