16 KANSAS CITY REVIEW OF SCIENCE. 



too noisy, too irregular, and sometimes uncertain, but the advances made are 

 very marked and very encouraging. The hall in which we are is, as you see, 

 brilliantly illuminated by a gas-engine. Those little lamps, though electric glow 

 lamps, are in fact lighted by gas, though the gas itself is consumed in the cellar. 

 The light we enjoy is only a form of the energy which has been brought into this 

 building by the Gas Light and Coke Company. In all cases of electric lighting 

 electricity is merely the agent which transforms the pent-up energy contained in 

 water, steam, or gas, into that of light. Hence it is that so much of the efficiency 

 of electric lighting apparatus depends upon the instrument called the " dynamo," 

 by which the conversion of this energy is brought about, and here it is that so 

 much inventive skill has been expended, and so much real progress has been 

 made. 



The tendency of recent improvements has been to improve the mechanical 

 details, and to increase the output of the smaller machines. Thus by increasing 

 the quantity and quality of iron, by better winding, and by re-arranging some 

 parts of the machines, Dr. Hopkinson has succeeded in doubhng the output of 

 the Edison dynamo. Mr. Crompton, by somewhat similar means, and by using 

 the purest iron obtainable, has succeded in making his Biirgin dynamo light up 

 2IO lamps, instead of 90. Sir William Thomson and Mr. Ferranti have turned 

 out a little machine which succeeds in lighting up 1,000 lamps by a mass of 

 metal, which two years ago would not have illuminated 100 similar lamps. 



Thus we have a process which is still actively going on, by which the eco- 

 nomical output of a given weight of material is vastly increased. 



One of the most interesting objects at the Fisheries Exhibition last year was 

 the Hochhausen dynamo, which is one of the most remarkable yet brought into 

 the market. Those who visit the forthcoming Health Exhibition will have an 

 opportunity of inspecting it. The main features of this dynamo are the extreme 

 simplicity and mechanical accuracy of its parts, the automatic mode of govern- 

 ing, its great adaptability, so that it can be varied at will either to high or low 

 tension, and the remarkably low velocity for such high electro-motive force. 



The distribution of the currents through conductors is one of the problems 

 that demands the highest skill of the engineer, not alone for the efficient work- 

 ing of the system, but for its economy. It is not sufficient to convert our useful 

 energy into electric currents, we want to distribute them with the least possible 

 waste. Conduction means waste, and this waste can be controlled only by using 

 the purest metal, and by so regulating the electro-motive force and dimensions of 

 the conductor as to obtain the maximum effect with the minimum means. It is 

 an exceedingly difficult problem to solve. The metal universally used is copper, 

 but very few people take the precaution to test its purity. Contractors go to the 

 cheapest market, and the result is they get the nastiest material. I know of 

 conductors that give only 70 per cent of the conductivity that they should give. 

 This means largely increased waste, and greatly enhanced cost of working. 

 Impure copper not only means needless waste, but waste means heat, and there- 

 fore danger. 



