TRANSACTIONS OF SECTION G. 667 



gave an account of an experiment lately tried, by wliicli communication had been 

 effected between Southampton and the Isle of Wight across the Soleiit, the object 

 being to trv the possibility of establishing communication across seas and channels 

 by telephone without the aid of wires. Large metal plates were innnersed in the 

 sea at opposite ends of the Solent— namely, at Portsmouth and liyde, six miles 

 apart, and at Hurst Castle and Sconce Point, one mile apart. The Portsmouth and 

 Hurst Castle plates were connected by a wire passing tlirough Southampton, and 

 the Rydc and Sconce Point plates by a wire passiug through Newport ; tlie circuit 

 was completed liy the sea, and signals were passed which could be read liy the 

 Morse system, but speech was not possible. 



3. Oa a new Arc Lawi). By W. H. Preece, F.R.S. 



This is the invention of M. Abdank, a Polish professor residing in Paris. He 

 separates the regulator of the current from the lamp itself, and hxes it anywhere 

 within easy inspection and manipulation. The regulator is a differential balance, 

 and it acts like the key of a jNIorse apparatus, which sends automatically short, 

 rapid, successive currents through a local break, so as to allow the top carbon to 

 fall by very minute movements as it ia consumed. The carbon is continually 

 falling by a motion invisible to the eye, but sufficient to provide for the consumption 

 of the carbons. It is a remarkably constant and steady arc lamp. Regulation by 

 small and successive steps automatically controlled is believed to be a new prhiciple. 



4. Recent Progress in Electric Railways. By Dr. Fleming. 



This paper described Edison's railway at Menlo Park, which the author said 

 saved about 1 lb. of coal per hour per horse-power as compared with the ordinary 

 locomotive. 



5. On Electric Light Engineering. By Dr. Fleming. 



6. On the Efficiency of the Edison Steam Dynamo. By Dr. Fleming. 



7. On some Ajiparatus for use in connection with Electric Light 

 Measurement, By Robert Sabine. 



The writer gives an account of four pieces of apparatus devised for the purpose, 

 ^•iz : — 



1. A photometer. 



2. A current dynamometer. 



3. A potential dynamometer and resistance measurer combined. 



4. A mean-pressure indicator. 



The principle employed in the photometer is tliat such a thickness of some 

 absorbing material is placed in the path of the rays of each of the two lights imder 

 comparison as will partly equalise the two lights, the final adjustment being made by 

 the alteration of the relative distances of the lights from the photometer. The current 

 dynamometer is formed of two flat coils, one of which is suspended, and the other 

 arranged to slide along a scale. Suitable arrangements are made for allowmg 

 the current to pass through the whole sj'stem. The repulsion between the coils 

 results in the deflection of the suspended coil. The sliding coil is then shifted 

 until the two coils are parallel. Tlie paper describes the way in which the scale is 

 graduated, and the arrangements for observing the deflection of the suspended coil. 



The potential dj'namometer and resistance measurer consists of two circular coils 

 of moderately fiiie copper wire, one of which is held by a bifilar wii"e suspension 

 inside the other, as in Weber's well-known dynamometer, an adjustable resistance 

 being inserted to reduce the deflections to a constant value. When required, how- 

 ever, to be used as a galvanometer the suspended coil can be readily removed and 

 replaced by a magnet needle. The object of the mean-pressure indicator is to 



