i8 



and automatically stopping the machine, this being the sign that the lead has struck the ground. 



Before however the machine has stopped there will be a certain amount of wire paid 

 out, from the time that the lead strikes the ground, and this slack is taken up by the scale in 

 its descent. At the same time the attendant presses the wire drum firmly against the friction 

 disc, and compresses the coil spring G with the adjusting wheel F. 



The counter can now be read off, giving the depth in metres if the wire is vertical. It 

 should here be noticed that during the paying out of the rope the adjusting wheel F is at 

 rest. A point to which special attention should be paid is that the tightening of the wiredrum 

 serves also to regulate the tension of the rope between the wiredrum and the winding-drum, 

 thus preventing the wire from flving out of the top-guide-pulley and getting damaged. The 

 man attending to this has therefore to keep a sharp look-out that the scale does not strike the 

 stops, which would cause a dangerous jerk in the wire. The man at the brake regulates it and 

 takes care that the wire is wound fairly on the drum without the strands overlapping one another. 



It was found that even with a well oiled winding-drum the rope would sometimes run 

 up the high side 'of the drum and suddenly shift back to the midclle thereby causing a momentary 

 slack in the rope and a jerky motion of the brake, consequently an unregular paying out of 

 the wire. To remedy this fault an iron lever was fitted and fixed to the machine which forced 

 the wire to keep in the centre of the drum during the winding. 



W'hile sounding, this lever was put to the lelt and when hauling in, to the right of the 

 coils and it answered very well. Of course the proper adjustment of the brake as well as the 

 required weights in the scale are matters which can only be found by experience. 



To find the speed of run it is only necessary to observe in what time a certain length, 

 say ioo metres, is payed out. Experience soon teaches this to be done by sight. 



The Le Blanc machine requires a rather heavy lead on account of the comparatively 

 great friction which has to be overcome. Especially when a great depth is anticipated it is 

 advisable to have a heavy lead, because otherwise the amount of rope run out would take up 

 too great a proportion of the total tension and reduce the chance of the machine being stopped 

 automatically, especially with a slight pitching of the ship, for it must be born in mind that the 

 sinker of the stray line must never be allowed to strike the bottom for in that event the line 

 kinks and breaks, on being hauled in. 



For the same reason a weight of 25 kilogrammes is but scarcely sufficiënt to overcome 

 the friction of the machine in case waterbottle and thermometers have been attached to the 

 lead itself. 



Before beginning to sound the machine should be oiled and the indicator set to the 

 depth at which the lead is suspended below the surface of the water. It should be ascertainecl 

 that the pointer of the indicator is tightly fixed on its spindle to prevent false indications. 



ó. When hauling in the line. 



Besides the three persons, above referred to, two more assistants are needed to attend 

 to the oilintr of the wire with oiled rags held in their hand. As soon as the lead reaches the 

 bottom and the register is read off, the brake and the friction adjusting wheel are released and 



