ma Lightning Conductors in Ships. 355 
long elastic continuous line ; the whole conductor is inserted under 
the edges of a neat groove, ploughed longitudinally in the aft side of 
the different masts, and secured in its position by wrought copper 
nails, so as to present a fair surface. The metallic line thus con- 
structed, will then pass downward from the copper spindle at the 
mast-head, along the aft sides of the royal-mast and top-gallant-mast, 
being connected in its course with the copper about the sheeve-holes. 
A copper lining in the aft side of the cap, through which the top- 
mast slides, now takes up the connection, and continues it over the 
cap, to the aft side of the top-mast, and so on as before, to the step 
ofthe mast. Here it meets a thick wide copper lining, turned round 
the step, under the heel of the mast, and resting on a similar layer of 
copper, fixed to the keelson. This last is connected with some of 
the keelson-bolts, and with three perpendicular bolts of copper, of 
two inches diameter, which are driven into the main keel upon three 
transverse or horizontal bolts, brought into immediate contact with 
the copper expanded over the bottom. ‘The laminz of copper are 
turned over the respective mast-heads, and secured about an inch or 
more down on the opposite side; the cap which corresponds is pre- 
pared in a somewhat similar way, the copper being continued from 
the lining in the aft part of the round hole, over the cap, into the 
fore part of the square one, where it is turned down and secured as 
before, so that when the cap is in its place, the contact is complete. 
n this way, we have, under all circumstances, a continuous metallic 
line, from the highest points to the sea, which will transmit the elec- 
tric matter directly through the keel,* being the line of least re- 
sistance. 
16. From what has been already observed, it will be apparent, 
that, in whatever position we suppose the sliding-masts to be placed, 
whether in a state of elongation or contraction, still the line of con- 
duction will remain perfect, for that part of the conductor which ne- 
cessarily remains below the cap and top, when the sliding masts are 
struck, is no longer in the line of action, consequently its influence 
heed not be considered. : 
17. The following table exhibits the mean proportion of a con- 
ductor thus constructed on one mast of a fifty gun frigate, as com- 
* Since the mizen-mast does not step on the keelson, it will be necessary to have 
‘metallic communication at the step of the mast with the perpendicular stancheon 
immediately under jt, aad so on to the keelson as before, or otherwise carry the con- 
ductor out at the sides of the vessel. 
+ 
