24 EEPORT OF THE SECRETARY. 



this effect. lu Baffin's bay the minimum pressure accompanied the 

 soutlieast wind, while at Port Kennedy the same effect was produced 

 by the northeast wind, and at Rensselaer harbor by the west and 

 northwest. The lowest reading of the barometer occurred just be- 

 fore the commencement of violent storms. 



Among the miscellaneous observations, perhaps the most import- 

 ant is one which relates to the aurora borealis. Captain McClintock 

 observed that the streamers in all cases of the exhibition of this 

 meteor appeared to come from the surface of open water, and not in 

 any case from the fields of ice. This observation would go far to 

 establish the truth of the hypothesis that auroral displays are due to 

 electrical discharges between the air and the earth, and that these 

 are interrupted by the interposed stratum of non-conducting ice. 



On the occasion of a visit of Lady Franklin last summer to the 

 Smithsonian Institution, I had the satisfaction of receiving, on behalf 

 of the Regents, her expressions of thanks for the discussion and publi- 

 cation of these observations, connected as they are with the memory 

 of her lamented husband. 



Another paper which has been accepted for publication is entitled 

 "Ancient Mining on the Shores of Lake Superior." This paper was 

 received in July, 1856, but, owing to imperfections in the manuscript, 

 its publication was indefinitely postponed. The subject, however, of 

 which it treats has lately received so much additional interest fi-om 

 the investigations of the archseologists of different parts of Europe 

 that we Avere induced to submit it again to the author for correction, 

 and to have a more accurate map of the mining region prepared, as 

 well as corrected drawings of the implements made, under the imme- 

 diate superintendence of the Institution. The wood-cuts are now in 

 the hands of the engraver, and the memoir will be prepared for dis- 

 tribution without unnecessary delay. 



On reference to the first volume of "Smithsonian Contributions" 

 it will be seen that among the contents of the mounds of the Missis- 

 sippi valley, as figured by Squier and Davis, are implements and 

 ornaments of copper, such as axes, chisels, knives, spear heads, 

 rings, bracelets, &c. The copper of these articles frequently contains 

 small portions of pure silver — perhaps originally in the form of crys- 

 tals — which serve in a measure to identify the source from which 

 the material came. Pure copper is comparatively a rare mineral, and 

 nowhere on the surface of the earth has it been found in greater 

 quantity and in larger masses than in that remarkable projection from 



