22 



the one side of the cylinder is cut away over a length of 250 millimetres. Around this part 

 revolves another thin tube or covering plate similarly cut away so that by turning this round, 

 the opening can be opened or closed. hor further protection an iron tube is passed over both 

 and held in place by a screw. The external diameter of this iron tube is the same as that ot 

 the cock shell namely 103 millimetres. 



The upper part of the gunmetal tube is of smaller diameter and provided with two 

 slots, which determine the amount of movement allowed to the wrought-iron tube or slip-bolt. 



The slip-bolt has two notches which project beyond the gunmetal tube when the lead 

 is suspended in the position of descending. On to the projections formed by these notches the 

 slinos of the bal last- weiedits are slunsf. 



The stray-line is looped to the link on the slip-bolt. When the lead has reached the 

 bottom, both ballast-weights and slip-bolt continue to descend ; this slips the slings of the ballast- 

 weights out of the notches, allowing them and the weights to fall off. As the lead is hauled 

 up and the weights slip right off, the cock is shut. 



The weight of the sounding lead is 15 kilogrammes. 



Besides this type others were used, of simpler and lighter construction and fitted with 

 butterfly valves for bringing up the bottom soil. For instance, a very effective deeplead was 

 made from a piece of boilertube. For shallow depths an ordinary lead of 25 kilogrammes 

 weight was used. This weight was found scarcely sufficiënt. There were further on board two 

 Sigsbee's leads with a conical valve. The slipping arrangement was also of a special construction. 

 The bottom part can be unscrewed to remove the mud that has been dredged. The external 

 diameter of the cylinder is 65 millimetres and the weight 2.7 kilogram. 



The ballast-weights used were cast iron cylindrical and spherical rings, with a hole of 

 115 millimeter diameter. The weight of the cylindrical ones was 9.25 kilogram and that of the 

 half spherical ones 13.25 kilogram. 



To be able to use these same weights with the Sigsbee leads, additional bushes were 

 used of 110 millimetres exterior diameter with a hole of 64 millimetres and they weighed 

 7.75 kilogram. 



In case of need any kind of weights may be employed such as projectiles, pieces of iron, 

 tins of sand etc. 



It is advisable always to hang them symmetrically to insure a vertical descent. 



If the bottom specimen is for scientific use the cock lead is preferable, especially in 

 muddy ground, because the hollow tube of the cocklead brings up on undisturbed cylindrical 

 bottom specimen in which the different layers of soil are exposed in their natural succession. 

 The only objection is that if the ground is hard or the cock fails to work it brings up nothing. 



The SlGSBEE lead has the advantage of being light, although being made of copper it 

 is apt to get damaged on stony ground. The chances of the slip arrangement not working 

 when muddy ground is encountered, is about the same as with the other type. How to relieve 

 the strain in the rope in such an event has already been explained. 



