164 



liiglily probable, that the different strata are alternately posi-' 

 tive and negative, typified in the coils of the electro-galvanic 

 series ; — where the positive insulated coil of copper induces a 

 necrative state in an insulated coil of wire above it, and thus 

 alternates in a series of six or seven coils. 



The electricity in the form of lightning during the past year 

 has been unusually active, but by the observations of Mr. Asa 

 Larason, of this city, the cases vrere not so numerous as in 

 the years 1846 and 1850. 



The number of electric exhibitions observed by him were 



Number. 



in isoi '^z m i04:U zi in 1849 24 





Number. 



J, 



Tumbe 



18S1 



22 



in 1840 



27 



1832 



19 



1841 



21 



1833 



18 



1842 



26 



1834 



26 



1843 



22 



1835 



20 



1844 



26 



1836 



16 



1845 



28 



1837 



15 



1846 



39 



1838 



27 



1847 



29 



1839 



21 



1848 



31 



1850 



37 



1851 



32 



1852 



29 



1853 



28 



1854 



32 



1855 



21 



1856 



34 



We perceive by this table that the number of electrical dis- 

 turbances observed by Mr. Lamson was less in 1856, than in 

 1846 and 1850 ; but of these discharges the number of those 

 of forked lightning in the year 1856 must have greatly pre- 

 ponderated. 



We may now consider and endeavor to answer the questions, 

 proposed for the consideration of the Institute by Rev. G. B. 

 Perry, and by it, referred to this Committee. 



1. Has the exemption of buildings through lightning rods, 

 been such as to justify the general confidence reposed in them ? 



To most of those who have given any attention to the subject, 

 it is a matter of surprise that any doubt should exist, that 

 luarly absolute safety tnay be secured by the use of rods 

 erected on scientific principles. 



Mr, Ebenezer Merriam, of Brooklyn, N. Y., in a communi- 

 cation to the Journal of Commerce, says, that he recorded 39 

 deaths by lightning, and 27 thunderstorms, in July, 1854. — 

 " Our record, says he, gives an aggregate of 750 deaths 

 on the land for the period of 14 years, only one of which 

 occurred in a building furnished with lightning conductors, 

 and that one in the summer of 1855. at Little Prairie, Wis- 

 consin. There were three buildings burnt by lightning in 



