370 Conducting Rods. 



to the earth, united with a screw and socket, and insulated from 

 the building by means of glass cups. 



That of Mr. Harris, consists of a double strip of copper, sunk 

 into each mast and spar by a shallow channel, to bring the metal 

 flush with the wood ; the strip being interrupted at every few feet 

 to give way readily with the bending of the spar, and still so as 

 to preserve its continuous extension. The strips extend from the 

 mizen mast to the stern-post, from the steps of the mast to the 

 metallic bolts passing through the kelson and keel to the water : 

 also bands of copper pass under the beams leading to the iron 

 knees or metallic fastenings, passing through the side of the ship, 

 the whole formed with shut joints, and making of the ship a com- 

 pound metallic mass, little liable to be destroyed by any electrical 

 shock to which it may be subjected ; this system has had a trial 

 of 18 years in the British navy, and even the common sailor has 

 merged his suspicion into admiration. 



The Committee declare it to be their opinion, that any system 

 of conductors, sufficiently elevated, presenting a sufficient number 

 of points, perfectly continuous, presenting competent surface, and 

 pursuing the most direct route to the earth, claims and should re- 

 ceive full confidence of the public. 



4. Are some trees better conductors than others, as the elm 

 for instance than the pine, and therefore more efficacious pro- 

 tectors ? 



In the cases of this nature which have been noticed the past 

 year, it has almost invariably been found that the pine when struck 

 has been shivered. But the elm receives the shock most patiently, 

 •perhaps its exceeding strength enables it better to bear the shock. 

 The oak usually manifests the effects of the contact. The North 

 American Indians have a tradition, which declares that the beech 

 is never struck by lightning. Tiberius, the emperor of Rome, 

 wore a wreath of laurel as a protection from lightning. Since 

 tradition is usually founded in truth, we may infer that, so far as 

 its authority extends, the affirmative is the true answer to this ques- 

 tion. 



Pospibly the trees whose branches make a small angle with the 

 trunk, are better conductors than those constructed with greater 

 angles The angles of the branches of the beech and the elm are 

 small ; those of the oak, the apple, the locust, the sycamore and 

 the pine are large. I have spent six years in the vicinity of a 



