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 among 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 

 by 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, 

 of fifteen sheets. 



On motion of Prof. Wm. B. Rogers — 



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

 Ticknor, Esq. for his very valuable present, transmitted through Na- 

 than Appleton, Esq., of a portion of Baron von Waltershausen's " iEtna 

 and its Convulsions." 



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

 hausen an expression of the great interest and satisfaction with which 

 they have inspected the admirable specimens of his " ^tna and its Con- 

 vulsions," and have read his letter accompanying them ; and that while 

 they offer him their cordial congratulations on the progress already 

 made in his great work, and earnestly sympathize in the zeal with 

 which he pursues his object in spite of obstacles, they look forward 

 with the greatest interest to the completion of his labor. 



Dr. Locke read a paper on the "Connection between Geology 

 and Magnetism," illustrated by beautiful transparencies, topo- 

 graphical and magnetic. Dr. Locke remarked — 



In the year 1838 I began to examine the elements of terrestrial mag- 

 netism, including dip, declination and intensity, both horizontal and 

 total, over various parts of the United States. Every year since, I 

 have made joui-neys to extend this kind of research, until now I have 

 embraced in a general way the region from Cambridge, in Massachu- 

 setts, westward to the extreme of Iowa, and from the middle of Ken- 

 tucky northward to the north side of Lake Superior. It was but natural 

 that I should note the geology of the substratum at each station ; and 

 on reducing my observations and putting them into tabular form, I ex- 

 amined the properties of each group, extending over rocks of a similar 

 kind, and found, so far as I had examined, some general indications by 



