Ixvi GENERAL SUMMARY OF SCIENTIFIC AND 



mination by the larger machine was only one hundredth of that of 

 the same light when obtained with oil, and only one fiftieth of that 

 obtained with coal gas. 



Some experiments have been made in Paris upon dividing the 

 electric light, under the direction of M. Baron. A single Gramme 

 machine has fed in this way not less than eighteen lamps, each of 

 which gave a light equal to 100 gas jets. 



Mouton has proposed a simplified method of determining the 

 internal resistance of a battery without complicated apparatus and 

 the sacrifice of much time. It gives the resistance in terms of that 

 of a certain shunt wire introduced into the circuit. 



Plants has continued his experiments with secondary batteries, 

 and now shows that the spark taken from the surface of water gives 

 phenomena analogous to those observed in polar auroras. 



Bourbouze has proposed to use natural conductors, such as water- 

 courses, and even the earth, as a medium through which to obtain 

 electric signals. Experiments which he has made in Paris seem to 

 have been quite successful. 



Girouard has described a new form of regulator for the electric 

 light, the essential point of which is the use of a balanced arm 

 separate from the carbon holder, and acting as a relay, through the 

 magnet of which the whole current passes. The current of a small 

 battery contained in its base is sent in one direction or the other, 

 according as the electro-magnet is weak or strong, and this deter- 

 mines the motion of the clock-work by which the carbon points are 

 separated or brought together. This balanced regulator has been 

 used in the United States for many years by Farmer. 



Holtz has described a new form of tube for electrical illumination, 

 which is an improvement upon the one devised by Gaugain, in 

 Avliich a series of funnels directs the discharge. In the new tube 

 there are one, two, or three diaphragms, in each of wdiich are two 

 funnel tubes facing opposite ways, those facing each way being on 

 a right line parallel to the axis of the tube. The effect is the same 

 as in Gaugain's tube, but the single tube is much more convenient. 



Oberbeck has given a new method of measuring the electric con- 

 ductivity of liquids. It consists in measuring the maximum strik- 

 ing distance between two balls of a given induction spark, and then 

 introducing as a lateral circuit the liquid to be measured, and again 

 measuring the spark. By making a series of observations and plot- 

 ting them, taking the lengths of the liquid columns as abscissas 

 and the spark length as ordinates, a curve of conductivities is very 

 readily obtained. 



Rowland has called attention to an error in Kohlrausch's deter- 

 mination of the absolute value of the Siemens mercury unit of 

 electrical resistance, which he thinks will account for the two per 

 cent, difference from the results of the British Association commit- 



