118 Mr. Snow Harris on Lightning Conductors 
metallic conductors have been from any cause placed along 
the masts or rigging, and in which the electric agency found 
its way through the hull to the sea. We should further ex- 
pect from him, something like an examination of the general 
nature and effects of electrical discharges, since it is clear, be- 
fore any accurate estimate can be arrived at, of the relative 
quantity of electricity likely to be discharged from a thunder- 
cloud, and the probable effects on metallic rods, or other 
conductors set up with a view of directing it in any given 
course, such information is quite indispensable. 
4. Now it is to be particularly observed, that Mr. Sturgeon’s 
memoir is really deficient in such information ; a few clumsy 
experiments in illustration of a well-known fact in electricit}^, 
deceptively associated, by means of a vague hypothesis, with 
some of the ordinary effects of lightning, on a ship not having 
any regular conductor, and with some every-day phaenomena 
of theelectrical kite, is virtually the amount of all that the author 
has advanced, under the imposing title of “ Theoretical and 
Experimental Researches.” 
5. In illustration of the careless way in which he meets this 
question, it may not be out of place to notice the following 
specimen of his inductive philosophy, —being the very outset 
of the comparison he has proposed, of tbe observed effects of 
lightning, and the probable effects on my conductors'^'. 
In the account given of the damage recently sustained by 
H.M. Ship Rodney, it appears, that the shock of lightning 
which shivered the top-gallant-mast, damaged the top-mast, 
8cc., &c., fell on a small brass sheave in the truck for signal 
halliards, and slightly fused it. This sheave weighed about 4 
ounces ; it was only about an inch and a half diameter, hol- 
lowed except at the centre and rim, where it was somewhere 
about half of an inch in thickness. The lightning also fell on 
the copper funnel for top-gallant rigging, being a hollow 
cylinder of 16 inches in length, 10 inches in diameter, and not 
quite a quarter of an inch thick. This funnel was not any- 
where fused. It fell also on other metallic masses, such as the 
iron-bound tie-block, on the top-sail-yard, &c., &c., the iron 
hoops of the mast, &c., on which no calorific effect was ap- 
parent. 
6. Now we have here something like evidence what was 
really the actual jpovoer of the charge. We see, for example, 
that it did not fuse a copper funnel, 16 inches long, 10 inches 
in diameter, and about |-th of an inch thick. In the face of 
which fact Mr. Sturgeon insists, that had the charge fallen on 
* Sturgeon’s Memoir, sec. 204. 
