430 



whenever the general temperature of the laboratory falls. 

 To this latter cause he ascribed differences of results ob- 

 tained in the morning and evening, amounting to twenty 

 per cent. He thought that under favorable circumstances 

 £lnd with requisite care, an approximation to accuracy can 

 be made within two per cent., and much closer than with 

 the Bunsen instrument. 



Professor Frazer communicated the fact of the discovery 

 of titanic iron, in the form of a perfect crystal and of 

 unusual size, half an inch on a side, associated with chlorite, 

 in chromic iron, at Frank Wood's Mine, in Lancaster 

 County, Pa. The specimen is in the possession of Mr. 

 Tyson, near King of Prussia, Chester County, Pa. A small 

 portion of the crystal was submitted to the blowpipe by 

 Prof. Brush. (The specimen is mentioned in Dr. F. A. 

 Genth's Report on the Mineralogy of Pennsylvania, Reports 

 of Progress of the Second Geological Survey, 1874.) 



Prof. Chase read a letter from Gov. Rawson, of Barba- 

 does, in which he writes that he expects to obtain the ap- 

 pointment, by Government, of a salaried ofhcer, intrusted 

 with the duty of continuing the meteorological observations 

 at Barbadoes, the importance of which is made the greater by 

 the fact that the island is near the hypothetical cradle of the 

 Atlantic cyclones and tornadoes of the Gulf of Mexico. 



Prof. Frazer described some microscopic sections of trap 

 dykes on the Mesozoic red sandstone of Pennsylvania and 

 Connecticut. He had taken specimens from the vicinity of 

 Gettysburg, both as slides and fragments, to New Haven, and 

 compared them with similar slides and fragments of the 

 Connecticut traps in the possession of Mr. E. S. Dana. 

 There were fine grained greenish dolerites exactly alike in 

 both localities. Coarse-grained gray rock, which in fragments 

 seemed identical, under the microscope showed differences 

 between the Connecticut and Pennsylvania varieties; that 

 of the former being merely a coarse-grained dolerite, while 

 that of the latter was a true syenite. He said : — 



During a recent trip to New Haven, I had the pleasure of examining the 



