548 MODERN INVENTIONS. 



series of notches cut in the wedge for that purpose, and lifting up the 

 wedge ; thus avoiding the necessity of slackening a single shroud. 

 This model also serves to demonstrate the plan of 

 HARRIS'S LIGHTNING CONDUCTORS. We have already briefly men- 

 tioned this surprising safeguard against the terrific explosion of the 

 electric fluid, to the destructive effects of which vessels are more liable 

 than any other objects; and we will now ^describe its peculiar arrange- 

 ment and advantages. To protect a ship effectually from damage by 

 lightning, it is essential that the conductor be as continuous and as 

 direct as possible, from the highest point to the sea ; that it be perma- 

 nently fixed in the masts, throughout their whole extent, so as to admit 

 of the motion of one portion of the mast upon another ; and that, in 

 case of the removal of any part of the mast, together with the conductor 

 attached to it, either from accident or design, the remaining; portion 

 should still be perfect, and equal to the transmission of an electrical 

 discharge into the sea. To fulfil these conditions, .pieces of sheet cop- 

 per, from one-sixteenth to one-eighth of an inch thick, varying from 

 one inch and a half to six inches in breadth, and being about two feet 

 long, according to the size of the masts, are inserted into the masts in 

 two laminae, one over the other ; the butts or joints of the one being 

 covered by the central portions of the other. The laminae are riveted 

 together at the butts, so as to form a long, elastic, and 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. This metallic line then passes downward from the copper 

 spindle at the mast head, along the aft sides of the royal mast, and top- 

 gallant-mast of large vessels, and is connected in its course with the 

 copper about the sheeve holes. A copper lining in the aft side of the 

 cap, through which the topmast slides, now takes up the connection, 

 and continues it over the cap to the aft side of the topmast, and so on, 

 as before, to the step of the 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, which is 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 laminae of 

 copper are turned over the respective mast heads, and are secured about 

 an inch or more down on the opposite side ; the cap which corresponds 

 is prepared 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. In this 

 way, we have, under all circumstances, a continuous metallic line frpm 

 the highest points to the sea, which will transmit the electric matter 

 directly through the keel, and emit it into the non-conducting fluid 

 where it becomes perfectly neutralized and harmless. 



A most interesting series of experiments, conducted by the inventor, 

 Mr. William Snow Harris, at Plymouth, as well as before the Lords of 

 the Admiralty, and subsequent trials on board of ships of war, have 

 shewn ti e decided superiority of this lightning conductor over that of 

 the chain; the latter being subject to frequent disarrangement and frac- 



