53 



The errors of the respective orbits, are as follows : those in longi- 

 tude being multiplied by the cosine of declinations. 





Errors of Parabolic 



Errors of Elliptic 



Date. 



Elements. 



Elements. 



Longitude. 



Latitude. 



Longitude. 



Latitude. 



Jan. 31 



+ 4.4 



+ 2.6 



+ O.G 



+ i'.8 



Feb. 12 



— 1.4 



— 1.9 



+ 0.4 



— 3.9 



23 



— 6.1 



+ 1.5 



— 2.6 



+ 2.0 



March 3 



— 2.7 



— 1.7 



+ 0.1 



+ 0.6 



12 



+ 0.1 



— 0.7 



+ 0.5 



+ 1.1 



24 



+ 5.9 



+ 1-1 



-f 0.9 



— 1.5 



Sum of Squares of Errors,' 



Sum of Squares of Errors, 





117.85 



34.62 



Mr. Loomis remarks, in conclusion, that there is no room for hesi- 

 tation in the choice between the two orbits, though the last element is 

 liable to considerable uncertainty. 



Mr. Boye communicated to the Society the results of the 

 analysis of three different varieties of felspar from the primary 

 rocks of the State of Delaware, as performed by Professor 

 Booth and himself. 



In the granitic veins that traverse the Serpentine, at Tucker's 

 quarry, six miles N. W. of Wilmington, the felspar occurs in large 

 masses, of which two different varieties may be distinguished ; one 

 having most of the characters of common potassa, felspar, or ortho- 

 clas, which is used for several technical purposes ; the other resem- 

 bling albite or soda-felspar, and exhibiting a peculiar tendency to un- 

 dergo decomposition. As these two varieties of felspar may be sup- 

 posed to enter generally into the composition of the gneiss and other 

 primary rocks of this region, and thereby affect, not merely their 

 mineralogical character, but also their stability when employed in 

 construction, or for other purposes, it was considered a matter of in- 

 terest to know their exact composition. They were, therefore, sub- 

 jected by Prof. Booth and Mr. Boye, to a thorough analysis by fusion 

 with three times their weight of carbonate of soda, &c. &c. To de- 

 termine their alkalies, they were decomposed by exposure on a shal- 

 low platinum capsule, to the vapours of fluohydric acid, in a close 

 leaden vessel as described by Brunner. The fluosilicates were then 

 decomposed by concentrated sulphuric acid, and the alumina precipi- 



