OF ARTS AND SCIENCES. 



221 



this among the manuscript papers in his custody, and con- 

 siders it as very interesting from its being an earlier survey 

 than that which is published in the first volume of the Smith- 

 sonian Contributions to Knowledge, with which it corre- 

 sponds in most particulars, while it exhibits some parts which 

 do not appear in the later chart, showing that some changes 

 may have taken place during the interval. 



Mr. Desor made some remarks on the columnar crystalliza- 

 tion of ice in gravel or clay, and offered an explanation of the 

 phenomenon, differing in some respects from that of a writer 

 in a late number of Jameson^s Jourfial. 



Further remarks on the subject were made by Professor 

 Rogers, Dr. C. T. Jackson, Mr. Treadwell, and others. 



Dr. C. T. Jackson, from the committee on coast marks, 

 submitted the following report : — 



" The committee appointed to consider the subject of permanent 

 coast marks for the determination of the future changes of level of 

 the coast of the United States, have attended to their duty, and beg 

 leave to present the following report. 



" It is now more than a century since the great Swedish philosopher, 

 Celsius, announced that, from observations made on the coast of 

 Sweden, he had arrived at the conclusion that the relative level of the 

 land and sea was not fixed, but that undoubted changes took place, 

 which he, at that time, ascribed to the subsidence of the waters of the 

 Baltic Sea. 



" It was not until the beginning of this century, that it was discov- 

 ered that the change, instead of being the result of a subsidence of 

 the waters, was due, on the contrary, to a gradual rise of the land. 

 The bearing of this discovery was too obvious to be overlooked. It 

 not only afforded the means of explaining many geological phenomena, 

 but it seemed also to involve the future destinies of all coasts under- 

 going similar changes. Surveys, accordingly, were ordered by the 

 Swedish government, as long ago as the year 1820, to discover the 

 amount of change in a given time ; and we are already in possession 

 of records, which enable us to estimate with accuracy the amount of 

 upheaval in many places. 



" The example set by the Swedish government has been followed 



