394 



Lieut Davis on the Prime Meridian. 



VII. On Nuttallite. 



Nuttallite was established as a species by Mr. Brooke,* on gen- 

 eral physical grounds, principally of hardness and color, and a 

 slight departure from the usual angles of scapolite. It was ana- 

 lyzed by Thomson,! who found for it a constitution so different 

 from scapolite, that it has been regarded as a distinct species by 

 many mineralogists, and is so placed by Nicol in his Manual just 

 published. I was induced to make a new analysis to decide the 

 doubt regarding its true constitution. The mineral is partially de- 

 composed by strong chlorohydric acid with heat, but it is not thus 

 possible to obtain a complete analysis. The mineral is found at 

 Bolton, Mass., in a white cleavable limestone with black augite. 

 Having a good specimen, I requested Mr. Ludwig Stadtmuller, 

 one of our pupils, to undertake the analysis. The following are 

 the results confirmed by several trials. The alkaline constituents 

 being determined by fusion with carbonate of baryta. 



Silica, 

 Alumina, ♦ 

 Perox. iron, 

 Lime, 

 Potash 

 Soda, 



Manganese 

 Water, 



? 



45-791 

 30107 



1-861 



17-406 



3-486 



traces. 



1-630 



100281 



It is obvious from simple inspection, that this analysis corres- 

 ponds exactly with scapolite, and we have no hesitation in refer- 

 ring nuttallite to scapolite. 



Analytical Laboratory, Yale College, September 15, 1849. 



Art. XXX. — On the Prime Meridian ; by Lieut. Davis, U.S.N. 



[Read before the American Association for the Promotion of Science, Aug. 15, 1849.J 



The question is, whether, having a National Observatory, and 

 being about to publish an American Nautical Almanac, we shall 

 still continue to count our longitude from the meridian of Green- 

 wich, or whether it is preferable for convenience, for accuracy? 

 or for other reasons, to establish a new Prime Meridian on this 

 continent. 



I will endeavor to treat this question fully, and to present all 

 the practical and scientific views in relation to it of which I am 



i 



* Ann. of Philos., xli, p. 366 



f N. York Lyceum Nat, Hist., vol. iii, p. 82 



• 



