SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. 



L66 



RECORDS AM) RESULTS 



MAGNETIC SURVEY OF PENNSYLVANIA 



AND TARTS OF ADJACENT STATES, 



1840 AND 1841, WITH SOME ADDITIONAL RECORDS AND RESULTS OF L834-35 



1843 AND L862, AND A MAP. 



BY 



A. 1). BACHE, LL.D., F.R.S., 



MEM. CORK. ACAD. BC. PARIS; PRF.ST. NAT. ACAD. SCIENCES J SUPERINTENDENT U. S. COAST SURVEY. 



[accepted fur publication, prbki 1 1! v , L863 | 



