INDEX. 



367 



Penn, Thomas, letter from, 358. 

 Planets Uranus and Neptune, 15, 20. 

 Plumbago, from Bucks county, 171. 

 Potassium, in iron ore, 264. 

 President and two members visit Eu- 

 rope, 322. 

 Protococcus nivalis, 262. 

 Publication fund established, 270. 



Radiation of heat, 109. 

 Reptilian footmarks, 91. 

 Rittenhouse, portrait copied, 156. 



Salt-radical theory, 275. 

 Schumacher, Prof., notice of labours 



ordered, 182 ; testimonial to, 185. 

 Secretary of Navy, resolution, 299. 

 Sound, transmission of, 118. 

 Spy-glass by Mertz and Son, 41. 



Taylor, R. C, Hillsborough asphal- 

 tum, 241. 



Telegraphic clock, 51. 



operations of XJ. S. Coast 



Survey, 74. record of observa- 

 tions, 206. 



Telescopic gas-holder, 164. 



Temperature of congelation, 168. 



Tilghman, R. A., leave to publish, 6; 

 potassium in iron ore, 264 ; decom- 

 position of alkaline sulphates, 274. 



Treasurer, annual report of, 46, 112, 

 171, 283, 358. 



Trego, C. B., abstract of memoir on 

 ancient Roman disc, 125; "Indian 

 walk" in 1737, 126; Cicada septen- 

 decem, 209; elected treasurer, 216; 

 minerals from New Mexico, 291, 

 294. 



Trust funds, 270. 



Tucker, Prof., probable effects of in- 

 crease of gold, 148. 



Unios from Ohio, 153. 



Vegetables from Arctic ice, 266. 



Walker, S. C, planet Neptune, 20; 

 Telegraphic operations of coast 

 survey, 74; Kirkwood's analogy, 

 97. 



Washington half dollar, 170. 



Wetherill, C. M., sulph. ox. ethyle, 

 &c., 30; minerals from Reading, 

 273 ; new variety of asphalt, 279. 



Wheat worm, 162. 



Wire gauze in myopy, 171. 



Wools from Saxony, 247, 250, 257, 

 264. 



Zircon, 273. 



Zinc, silicate of, 329. 



