34 Experiments on the Adhesion of Iron Spikes, 



formation appears very deficient in mineralogical interest. I have 

 not seen in it any minerals, except quartz and sulphuret of iron. In 

 some places it furnishes good roofing slate, and I have been informed 

 that a vein of limestone occurs in the rocks near Ticonic Falls at 

 Waterville, but I had not an opportunity of examining this place. I 

 have called the formation Argillite from its prevailing character, al- 

 though in some places it resembles talcose slate, and at others gray- 

 wacke. 



I think it worthy of remark, that the valley of the Kennebeck, 

 from Waterville, as far north as I had an opportunity of observing 

 during my visit in 1832 to Mount Abraham, is covered with boul- 

 ders of granite, of so peculiar a character that they may perhaps 

 some day be traced to their original position. These boulders dif- 

 fer from those observed on the Penobscot, by containing large im- 

 bedded crystals of white feldspar, which make the masses appear at 

 a little distance as if they were covered with broad chalk marks. 

 These crystals are generally about three inches long and one fourth 

 of an inch wide. I have seen some, however, five inches long by 

 four wide. 



I hope soon to be able to send you an account of the botanical 

 observations vt'hich I have made in the vicinity of Waterville: in 

 the mean time I send this hasty article, hoping that the few facts it 

 contains respecting the geology and botany of the regions visited,/ 

 will be received with interest, on account of the few notices which 

 have hitherto been published upon these departments of the natural 

 history of Maine. 



West Point, Aug. 31, 1836. 



Akt. III. — Experiments on the Adhesion of Iron Spikes of various 

 forms, when driven into different species of Timber; by Walter 

 R. Johnson, Professor of Mechanics and Natural Philosophy in 

 the Franklin Institute, Philadelphia. 



In reference to rail-road constructions, bridge-building, and sev- 

 eral other useful applications in civil engineering, as well as in naval 

 architecture, the adhesion of spikes, bolts and nails of various forms 

 becomes an object of much practical importance. In regard to rail- 

 roads, this matter is worthy of more attention than might at first sight 



