SCIENTIFIC SURVEY. 



373 



Moulding Sand. 

 The sand used in foundries for moulding must be of peculiar 

 material and texture, or consistence. It should be uniformly fine 

 as to its grains, that it may not give too rough a surface to the 

 castings. It should not have a sufficiency of clay or aluminous 

 particles to make it sticky, and yet enough to render it compact 

 and comparatively solid, when wet and packed or tamped into the 

 moulds. It should also not be so absorbent of water as to take it 

 too long a time to dry, after being moistened. It is difficult to 

 find deposits of sand possessing all these requisites. We were 

 informed by Hon. Shepard Gary, that he had found a good deposit 

 of this kind of moulding sand near his iron foundry in Iloulton, 

 which affords him a supply of an excellent quality and which he 

 uses altogether in his iron works. 



Helderherg Limestones and Marbles. 



Among other objects of this expedition, I was requested to trace 

 out what I could of the localities and boundaries of the lower Ilel- 

 derberg marbles, or Limestone formations, that occur in this sec- 

 tion of the State, and report to j'ou. I have done in regard to it 

 what the shortness of the time and the lack of some facilities 

 allowed me. The more and further I searched into this brandi of 

 our geological formations, the more impressed I became of the 

 ultimate value they will be to this section, and indeed to the whole 

 State, and of the importance of longer time being devoted exclu- 

 sively to their study and examination. A belt, or formation of 

 rock, which, as I found, stretches in a continuous direction across 

 not less than five townships, occasionally cropping out, and 

 at each locality of its appearance exhibiting surroundings and 

 accompaniments each of different character, could not bo thorough- 

 ly explored and all its characteristics ascertained in the three or 

 four weeks allotted to this section, and that time interrupted by a 

 search for objects pertaining to other branches of Natural History. 



On page 394 ©f your first report, in speaking of the geology of 

 the Wassattiquoik while on your way to Katahdin, you observe that 

 " on the Wassattiquoik, near its mouth, we found ledges of a bluish 

 quartz rock very evenly stratified. * * * Above them, on the 

 bank, the boulders and large masses of limestone similar to those 

 seen at Whetstone falls are so numerous that we believe the rock 



