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The letter below on lightning rods illustrates Henry's concern over the exaggerated claims  of some inventors and his impatience with non-scientists who ventured into scientific   waters. Henry had been studying various aspects of lightning, including its conduction   through lightning rods. In the 1840s, his advice would be sought on protecting the U.S.  Capitol Building in Washington and Independence Hall in Philadelphia from lightning.  

   
 



[August 1, 1838]19

                   HENRY TO THE EDITOR OF THE NEWARK DAILY ADVERTISER





   



Mr Editor 20
You published a few days since a certificate signed by a number of highly respectable   gentlemen in favour of an improved modification of the lightning rod,21 invented by Dr King22 of Boston. The certificate states, that the principal feature in the new rod consists in its presenting points to the atmosphere, in all directions &c. We have no personal knowledge of Dr King and would be sorry unjustly to disparage his   invention yet a sense of duty to the Public compells us to state, that the new modification of     the rod, appears to us not founded on sound philosophical principles. 

 In the first place, it is a well established fact, that, a single point becomes much more highly  electrified and consequently acts at a much greater distance than a ball under the same circumstances; or than a point in the vicinity and under the influence, of other points. These  considerations appear to have induced the French Philosophers to reccommend but one point  at the upper end of the rod.23

 Again, a number of points, along the course of the rod, would as it appears to us tend to   give off the electricity; and thus produce dangerous consequences from the lateral action of    the discharge.
With these views, until some new principle be discovered in Electricity, we shall adhere to  the well known form of the conductor reccommended in a report to the French Academy of  Sciences in 1824 by Poisson, Fresnel, Gay Lussac and others. 

One word in reference to the highly respectable names attached to the certificate. We  would say that in all ordinary matters we would pay them sincerely due defference but in the  present instance, endorsing an improvement in science, they loose with us a little of their  wonted influence.24

            F.25
 

 (Private note)
I have long intended to commence furnishing you from time to time with some small   contributions in the way of science.26 I have however constantly thought myself too much   engaged in other matters. If you can decipher the scrawl please give the article on the other leaf a place in your paper. It is intended as much for the gentlemen who have signed the certificate as for Dr King.27

                                                                 With Respect & Esteem
                                                                 In haste yours
                                                                 J.H.           

     


One word in reference to the <highly respectable> opinions of the highly respectable   Gentlemen who have signed the certificate. These in all ordinary matters would be received by   us with due respect and attention but in the present instance endorsing a scientific invention we do think they lose a little of their wonted influence.



Draft, Henry Papers, Smithsonian Archives. Published in Nathan Reingold et al., eds. The   Papers of Joseph Henry, vol. 4, January 1838-December 1840: The Princeton Years   (Washington, 1981), pp. 81-83.