19 



the winding-drum is worked round a few revolutions untill the lead is lifted off the bottom. 

 This will usually cause the scale to be raised and remain suspended unless the depth is insuf- 

 ficiënt. Should the scale however remain tightly pressing against the upper stops, the probability 

 is that the weights have not been dropped. To accomplice this the lead is then lifted up about 

 1 5 or 20 metres and lowered once more. If however the bottom is of a soft muddy nature 

 even this will not accomplish it because the weights will sink in the mud and the decrease in 

 tension will not take place suddenly enough. The slow descent of the scale will indicate this. 



If the bottom is hard the scale will sink abruptly and then the adjusting wheel has to 

 be screwed up sharply to prevent the wire from slipping out of the top pulley. 



In case of soft muddy ground however the brake acts before sufficiënt slack is given 

 to the rope to detatch the slip block from the lead (or as in case of the Sigsbee lead to work 

 the sliphook). The slipblock of the Le Blanc lead is fairly light and with the weights resting on 

 the soft ground there is scarcely sufficiënt power to pull it down farther. If the waterlayers 

 through which the wire passes have different currents a certain tension is mantained in the 

 rope which prevent the slipping apparatus from working properly. In this case the only chance 

 of dropping the weights is as follows. 



About twenty five metres of line is hauled in either by hand or by steam, some-one 

 stands on the ballastscale to keep it right down, the line is now paid out again at the normal 

 speed but a few metres more are allowed as soon as the lead has touched the ground, this is 

 observable by the reduced speed of the line, the less amount of tension as well as the indications 

 of the counter. The brake can be somewhat loosened during this operation. 



The stray-line and slipblock are now free to sink lower, even should the lead and weights 

 have already entered the mud. 



Now, provided the strops with which the weights are attached to the lead are not too 

 stiff and not too tightly fixed, both lead and weights will detach themselves from the slipblocks 

 and remain behind when the wire is hauled in. 



As soon as the lead strikes ground the winch is started to run free ; after the lead has 

 been lifted by hand and the weights slipped, the winch is put into gear and the line hauled 

 in with the scale heavely weighted. In stormy weather the scale must however not be weighted 

 quite down ; if the sea is rough it is better that the scale balances below the centre and prevents 

 it from striking the upper stops by hand. 



With a lead of 15 kilogrammes or less, 75 or 80 metres per minute was found to be 

 a suitable speed. 



When hauling in the line, the brake is set entirely loose. 



The adjusting-wheel should be set to keep a moderate tension between the two drums. 



Too much tension might damage the wiredrum ; too little tension is apt to lead to 

 irregularities in the winding. The result of this being that at the next sounding the wire may 

 leap out of the top-guide-pulley. 



Neat and regular winding is a very important point. 



During the hauling in of the wire it is passed through an oiled leather held in the right 

 hand ; while the left hand works the adjusting wheel. 



