402 INi)EX. 



Plough, American, 190 

 Plumbago in coal-gas retorts, 380 

 Porosity ofglass and silicious bodies, 192 

 Porter Dr. J. localities of minerals, 58, 252 



J. H. U. notice of Roxburj' rocking stone, 59 



Portugal, 198 



Potatoes, employment of in steam engine boilers, 193 



Precession of the equinoxes, remarks on, 328 



Primitive forms of crystals, connexion of with the number of 



their axes of double refraction, 363 

 Printing design?, new method of, 191 

 Proteus of N. America, observations on, 63 

 Prussian Travellers, 195 

 Pseudomorphous granite, 22 

 Public Education, notice of a new work on, 161 



Instruction, method of J. Ordinaire, 199, 383 



Pyro-citric acid, 187 



Pyrotechny, history of, 137 



Pyroxene of Sparta, N. J. analysis of, 145 



a 



Qjiartz smoky, 48 — grey, 48 — milky, 48 

 Q,uinby A. B. on Crank motion, 316 



K. 



Rain-gage, description of an improved, 426 



Rapids, navigation of, 175 



Rhubarb, Sulphate of, 385 



Rock formations of the Connecticut, Tabular arrangement of, 24 



Rocks accompanying Anthracite, remarks on, 260 



, remarks on the systematic arrangement of, 261 



Rocking stone, Roxbury, Mass. 59 



, Warwick, R.I. 201 



Rockmg stones, 157 

 Roxbury Rocking stone, 59 



Salt, essay on, 360 



Saw moved by mechanism, 198 



Scapolite, 53 



Sceneiy of the Connecticut, 1 



Scented fires, 132 



Schoolcraft H. R. on the copper of lake Superior, 43 



localities of minerals, 46 



Schweinfurt green, 386 



