362 Copper Sheathing. [Nov. 



bite. The original specimen is said to have been found in New 

 London, which place is not more than 25 miles from Haddam. 

 It is true that the largest piece of ore yet seen from the latter 

 locality, does not much exceed half an inch in diameter, while 

 that in the* British Museum is said to weigh several ounces ; * 

 but it is reasonable to expect, that when the new locality is tho- 

 roughly explored, masses of considerable size will be discovered. 

 There is another circumstance which favours the opinion that 

 the mineral analyzed by Mr. Hatchettis of the same variety, and 

 from the same locality, as that of Haddam, which is, the specific 

 gravity of the latter. The North American columbite was found 

 by Dr. Wollaston to be much lighter than that of Sweden ; the 

 cause of which was supposed to be small cavities in the former ; 

 and in confirmation of this opinion, I would mention that the 

 Haddam columbite, when immersed in water, continued to give 

 out minute bubbles of air for a considerable time, after which 

 the specific gravity was much increased. 



Article X. 



On the Misstatements in the Morning Chronicle and Times Neia- 

 papers respecting Sir Humphry Davy's Method of protecting 

 the Copper Sheathing of Ships' Bottoms. 



In my answer to an attack on the originality of Sir Humphry 

 Davy's plan for defending the copper sheathing of ships,f I 

 have said that the defended metal is more liable to become foul 

 from the adhesion of weeds, barnacles, £cc. than the undefended. 

 Such a statement first appeared in a provincial paper about 

 June or July last, and was copied into some of the London daily 

 prints, but I cannot now recollect the names of either the one 

 or the other, a circumstance, however, of no consequence to my 

 present purpose. The fact was stated in positive teruis, and I 

 was informed by what I believed to be good authority, that it 

 was correct. 1 was the less anxious to inquire more particularly 

 into it, because, even if true to the full extent, I felt convinced 

 that Sir Humphry Davy would find no difficulty in obviating the 

 evil, by reducing the energy of the defensive action; and my 

 conviction on that head remains unshaken. Had my inquiries, 

 however, been more minute, I should have been more guarded 

 in admitting the fact as a general result ; for I have since learned 

 that the assertion requires much qualification to make it consist- 

 ent with truth. 



I do not know whether or not the passage in question has 



* It weighs exactly 302*46 grains. — C. 



•j- Annals of Philosophy, vol. viii. (New Series) p, 141. 



