120 Mr. Snow Harris on Lightning Conductors 



tinor in a point, and equalizing with inconceivable rapidity the 

 disturbed electrical state of the sea and clouds. 



8. The manifest deficiency of sound practical information in 

 Mr. Sturgeon's memoir, imposes upon me the necessity of ad- 

 verting to the general character and operation of common 

 electrical discharges, whether produced by artificial means or 

 on the great scale of nature. In doing this I have no desire 

 to excuse myself, in case I should not have written clearly and 

 explicitly on the subject, since in no department of physics is 

 the field of observation so fertile, and the path of experiment 

 so sui-e and easy. We have before us the experience of nearly 

 a century, during which time lightning-rods have been em- 

 ployed ; a great number of instances have occuri'ed of shocks 

 of lightning falling on ships under a variety of different cir- 

 cumstances, in some cases where lightning conductors have 

 been present, in others where absent ; in many instances where 

 ships have been near each other and exposed to the same 

 storm, some having conductors, others not. The general laws 

 of the discharge are traceable in them all, and the effects on 

 metallic bodies distinctly shown. On the other hand, we can 

 on a minor scale, imitate successfully the great operations of 

 nature, and examine experimentally every possible contin- 

 gency attendant on the operation of a shock of lightning in a 

 ship. It is our own fault, therefore, if we do not treat the 

 subject scientifically, and arrive at complete practical solutions 

 of such questions as these: Is a lightning conductor desirable 

 in a ship? Will it cause by attraction a shock of lightning to 

 fall on a ship when otherwise such would not take place ? If 

 so, can it cause damage by its inability to get rid of the light- 

 ning which falls on it ? What is the best form and dimensions 

 of a lightning conductor for a ship ? What is the greatest 

 probable force of lightning to which it may become exposed? 

 Is it liable to cause damage by any lateral operation of the 

 charge passing through it ? I say, if such questions as these 

 cannot now be reasonably determined they probably never 

 can ; and, therefore, any one who writes or reasons obscurely 

 about them, and without due regard to a good induction of 

 facts, can have no claim to be considered as a sound reasoner 

 in experimental science; for, as beautifully observed by 

 Lord Bacon, " Man, who is the servant of nature, can act and 

 understand no further than he has, either in operation or in 

 contemplation, observed of the method and order of nature." 

 Under these impressions I proceed to examine the general 

 character and effects of electrical discharges as exhibited arti- 

 ficially, and on the great scale of nature. 



9. Although some theoretical differences may have arisen 



