Intelligence and Miscellaneous Articles. 143 



2. " Description of Fragmentary Indications of a huge kind of 

 Theriodont Eeptile (Titanosuchus ferox, Owen), from Beaufort West, 

 Gough Tract, Cape of Good Hope." By Prof. E. Owen, C.B., F.E.S., 



F.G.S. 



3. " Notes on the Consolidated Beach at Pernambuco." By J. C. 

 Hawkshaw, Esq., M.A., F.G.S. 



The consolidated beach at Pernambuco, which has already at- 

 tracted considerable notice, is a ridge of sandstone from 25 to 75 

 yards wide, and, as shown by borings made under the author's 

 direction, from 10 to 13 feet thick. The landward or higher edge 

 is nearly at the spring-tide high -water level ; and it slopes seaward, 

 the river (with a depth of 28 feet at low water 60 feet from the 

 rock) flowing along the former face. The rise and fall of spring 

 tides is 7 feet. Beneath the above rock is a stratum of sand with 

 shells and stones about 8 feet thick, and then a second layer of 

 sandstone rock. 



The consolidated beach is cemented by carbonate of lime, which 

 the author considers to have been deposited by the action of water 

 percolating through the rock, probably when the level of the land 

 differed somewhat from what it is at present. He thinks it possible 

 that this and other similar beaches on the Brazilian coast may mark 

 periods of repose in the slow vertical movements which the coast has 

 undergone. 



XXVI. Intelligence and Miscellaneous Articles. 



NOTE ON ELECTROMAGNETS IN TELEGRAPHY. 

 BY OLIVER HEAVISLDE. 



TN a recent Number of this Journal I stated : — " On telephonic 

 -*- circuits the reduction in current-strength is nearly inversely 

 proportional to the pitch of the sound," &c. This is only true for 

 a constant electromotive force. Thus it would be correct for a 

 battery telephone. The strength of very rapid currents from a 

 battery through an electromagnet is nearly inversely proportional 

 to the rapidity. But in an electromagnetic telephone, although the 

 electromotive impulse produced by a semivibration of the iron disk 

 of the sending telephone is constant for all pitches, provided the am- 

 plitude of the vibration is the same, yet when the semivibration is 

 executed in half the time, the mean value of the electromotive force 

 is doubled. Thus, instead of the second partial tone of a conti- 

 nuous sound being weakened nearly twice as much as the first, it 

 will not be quite so much weakened. Y being the current, E the 



resistance, L the electromagnetic capacity, and m= — , where T is 

 the time of a complete vibration, then ■*■ 



raE 



r= 



in the case of a Bell telephone, where E is proportional to the am- 

 plitude of vibration of the sending disk. Keeping E constant, r 

 increases slightly with m. Also, when E is increased, r is reduced 

 more for low pitches than for high. 



