Association of American Geologists and Naturalists. 101 



gent public, it would be my wish that my work should be spread in 

 America, particularly since so great a taste prevails anion* you for 

 the study of geology. The accompanying plates I send you only that 

 you may form an idea of the execution of the work, and in the course 

 of the next year I will send you the first number. 



I must add yet a few words about the engravings. They have been 

 drawn from nature with strict accuracy, chiefly with my own hand, or 

 at least under my supervision ; and as they are proof impressions, still 

 unlettered, I have written the titles in pencil. Then comes a proof of 

 a small portion of the topographical map, which, surveyed and drawn 

 y myself, like the accompanying sheet, in the proportion of 1 to 

 50,000, is engraved here by the master hand of Cavallari, of Palermo, 

 a man of great talent. The whole topographical map will be, if pos- 

 sible, still more perfectly executed, and consists, as above mentioned, 



01 nftpon clin^t^ 



of fifteen sheets. 



Prof. Wm. B. Rogers 



iEtna 



tesohed, That the thanks of the Association be presented to George 

 , 1C " or ' Esc h for his very valuable present, transmitted through Na 

 a « Appleton, Esq., of a portion of Baron von Waltershausen's ' ~ 

 *>« its Convulsions." 



^Resolved further, That the Association tender to Baron von Walters- 

 a «sea an expression of the great interest and satisfaction with which 



vubi m inSpected the admira ble specimens of his " jEtna and its Con- 

 ^sions," an d nave read hig Ietter accompany j n g them . and that wni]e 



mad ° 6r • hlm theif cordiaI congratulations on the progress already 

 whi 1 h hlS ^^ W ° rk ' and earnestl y sympathize in the zeal with 

 with th PUrSUes his ob J ect in s P ite of obstacles, they look forward 

 ne greatest interest to the completion of his labor. 



and \ L ° cke rea(i a P a P er on tne "Connection between Geology 



agnetism," illustrated by beautiful transparencies, topo- 

 8 jphical and magnetic. Dr. Locke remarked— 



net' e 7 ear 1^38 I began to examine the elements of terrestrial mag- 

 lot 1 ' m ° n g ^ip, declination and intensity, both horizontal and 

 hav ' ° Ver Various Parts of the United States. Every year since, I 

 emb e r made Journeys to extend this kind of research, until now I have 

 sett m a £ enenu " wa y the region from Cambridge, in Massachu- 



tuck' WeStWard t0 the extreme of Iowa, and from the middle of Ken- 

 that \ T rthward t0 the north side of Lake Superior. It was but natural 

 °n i d n ° te tbe geology o 1 " the substratum at each station ; and 



am - . C ' n § m y observations and putting them into tabular form, I ex- 

 kind a C ^ ro P ert i es of each group, extending over rocks of a similar 



ound, so far as I had examined, some general indications by 



