438 Official Correspondence on the attaching oj 



must also iron attract it, though in an inferior degree. On this poinl 

 however, facts are wanting to guide our opinions, and so much variety 

 of sentiment in regard to it pervades the scientific world, that we would 

 not be considered as expressing any decisive opinion on it. Dr. 

 O'Shaughnessy has proposed iron conductors protected by zinc plates, 

 but Mr. Danieli considers that this arrangement would not by any 

 means be efficient in preserving the conductors from oxidation, and 

 in this opinion we coincide, though we cannot but express a wish, that 

 the suggestion be put to the test of experiment. Conductors are daily 

 being erected in Calcutta ; would it not be well to settle the point in 

 question, by applying the zinc plates to them, and observing the result? 

 We have now laid before our readers the sentiments of Mr. Danieli, and 

 as before, would only farther record a single sentence of his report, in 

 which these are condensed. " These two reports (referring to the in- 

 structions drawn up by a Commission of the Academie Royale des Sciences, 

 and M. Arago's Report Sur le Tonurre) have really exhausted the sub- 

 ject, and ought to be sufficient in my opinion to convince the most pre- 

 judiced; first, of the impossibility of any additional danger arising from 

 lightning conductors of proper construction ; and, secondly, of the pro- 

 tection which they are competent to afford." It is thus apparent that 

 there is an entire coincidence of opinion between Messrs. Faraday 

 and Danieli as to the perfect efficiency of good conductors, when ap- 

 plied to Powder Magazines, and when to their testimony is superadded 

 that of Arago, Harris, and Wheatstone, each a master in electrical 

 science, we conceive our government would incur a fearful amount of 

 responsibility, were it to allow any departure from a plan sanctioned 

 by their favorable estimation, and tested by the experience of nearly 

 half a century. The reasoning of Dr. O'Shaughnessy in favor of his own 

 views, is" ingenious, and the facts he has adduced are valuable ; but 

 to deprive our Magazines of the protection they now possess, on the 

 authority of these alone, is a step we cannot believe government would 

 ever take. Nor would we recommend the plan proposed by Dr. 

 O'Shaughnessy (although theoretically we see no special objection to 

 it) in supercession of that now in use, till it has experience to the same 

 extent to plead in its favor, and some additional advantages to coun- 

 terbalance the additional expense it involves. We entreat government 

 to take no hasty steps in the matter, for an amount of human life 

 and property is at stake, which might well make the boldest pause. 

 Dr. O'Shaughnessy's own experience of the consequences of hastily 

 reasoning from the model to the machine, will have prepared him 

 fbr our caution in taking the minute results of experiments in the 



