Febeuaey 26, 1897.] 



SCIENCE. 



335 



exists between the Truro and Wellfleet 

 plains, the latter presenting steep ice-con- 

 tact (?) slopes towards the northwest. 



South of North Truro village, however, 

 the lower plain joins on directly to the 

 higher. Kettle holes are common. Standing 

 upon the high ground a mile north of Truro 

 station and looking east, the whole series 

 of plains seems to descend by a gentle delta 

 (?) slope toward the west, leaving a deep 

 and irregular depression occupied by the 

 Provincetown turnpike. In the vicinity of 

 Small's Hill a number of profound north- 

 east and southwest depressions dissect the 

 plain. These are occupied by the roads 

 leading to the east shore. The slopes on 

 both sides of these depressions are steep, 

 and although they probably have been 

 modified by wind the indications are that 

 they are due to former lobes of ice dissect- 

 ing the growing delta. Pamet Eiver com- 

 pletely divides this series of plains, the 

 southern portion being much more irregular 

 and hummocky than the northern and 

 also containing a number of kettle ponds. 



The Eastham Plains are typically devel- 

 oped about North Eastham village. This 

 series may be better regarded as one con- 

 tinuous plain uniform along the eastern 

 shore from Wellfleet to the ' Three Lights,' 

 where the elevation is about seventy-five 

 feet above the sea, and the whole plain 

 gently sloping westward. The northern 

 half of this large plain is dissected by dis- 

 continuous east and west, and northwest 

 and southeast depressions, with steep ice- 

 contact (?) slopes on the south and lobate 

 delta (?) slopes on the north. In the southern 

 half of the plain the depressions have a 

 north and south trend, with the steep ice- 

 contact (?) slopes on the west and the delta 

 (?) slopes on the east. South of Eastham 

 Centre the plain joins on to the moraine. 

 This plain was probably formed while the 

 Truro Plains were accumulating and after 

 the Wellfleet Plains had been formed. The 



latter seem to have been built by streams 

 from the north and east. The Truro 

 plains were built by streams from the 

 northwest and northeast, while the East- 

 ham Plain was being built by streams 

 from the east. The terminology is applied 

 to the slopes with some reservation, as al- 

 most the only criterion by which to judge 

 of their character is the relative steepness 

 and the general outline. Cuttings are very 

 rare, and hence the relative coarseness of 

 the material, and its disposition within the 

 plains cannot be ascertained. The sections 

 along the shore exhibit horizontal stratifi- 

 cation where not covered by talus. 



It seems difficult to believe that these 

 plains have not accumulated in static water 

 at the front of the much-dissected ice sheet. 

 Submarine accumulation seems improb- 

 able, as erosion scarps would have been 

 formed on the higher plains during the 

 formation of the lower. On the other hand, 

 if a body of fresh water was held up against 

 the moraine, in an embayment in the ice 

 front, it would be necessary to suppose that 

 the ice held on to the moraine from Barn- 

 stable eastward, and that a residuary plug 

 of ice filled the valley of Buzzard's Bay. 

 This latter necessity is probably the most 

 serious defect of the glacial lake theory. 

 Amadeus W. Geabau. 



A NEW METHOD OF DRIVING AN INDUCTION 

 COIL. 



Since the induction coil has come into 

 prominence through the discovery of the 

 X-rays of Rontgen considerable attention 

 has been turned toward devising some means 

 which is applicable to long runs, on a volt- 

 age such as is furnished by electric light 

 mains, 110 or 220 volts. The more recent 

 forms of break work well with storage bat- 

 teries, but these are troublesome, and a 

 break which will work satisfactorily on the 

 voltage of ordinary electric- light mains is 



