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446 Mr. H. Wilde on some Improvements in 



The strength and proportions of the several parts of the machine 

 enable it to be driven with advantage from 300 to 1000 revolu- 

 tions per minute. 



At the mediunvvelocity of 500 revolutions per minute the 

 major current will melt eight feet of iron wire 0*065 of an inch 

 in diameter (No. 16, B. W. G.), and will produce two electric 

 lights in series, each consuming carbons half an inch square at 

 the rate of three inches per hour. 



When driven at a velocity of 1000 revolutions (equivalent to 

 16,000 waves) per minute, the current will fuse twelve feet of 

 iron wire 0-075 of an inch in diameter (No. 15, B. W. G.) . As 

 soon as the heating or fusing of an iron wire of a given length 

 and section comes to be an acknowledged measure of powerful 

 electric currents, as well as a method of comparison between the 

 power of electromotors of different kinds, as it must ultimately 

 be, the significance of this result will be fully realized. 



At the velocity of 1000 revolutions per minute the light from 

 two sets of carbons in series is unendurably intense, as well as 

 painful to those exposed to its immediate influence. Estimated 

 on the basis afforded by the performance of the excellent mag- 

 neto-electric-light machines of MM. Auguste Berlioz and Van 

 Malderen, who have made a careful study of the photometric in- 

 tensity of the electric and oil lights, the power of the new 

 machine is equal to that of 1200 Carcel lamps, each burning 40 

 grammes (1*408 oz. avoird.) of oil per hour, or of 9600 wax 

 candles. The amount of mechanical energy expended in pro- 

 ducing this light is about 10 indicated horse-power. 



A comparison between the power of the new machine and that 

 of the 10-inch machine will show that while the current from 

 the former fuses twelve feet of iron wire 0*075 of an inch in 

 diameter, the current from the latter fuses only seven feet of 

 wire 0*065 of an inch in diameter, and is consequently only 

 about half as powerful as that from the new machine. Besides 

 this, the quantity of copper used in~ the construction of the new 

 machine is about 3^ hundredweight, and of iron 15 hundred- 

 weight, while the weight of these metals in the 10-inch machine 

 is 29 and 60 hundredweight respectively. In other words, we 

 have in the new machine a double amount of power with less 

 than one fourth the amount of materials employed in the con- 

 struction of the 10-inch machine. 



Another advantage possessed by the new machine is the great 

 reduction of temperature in the armatures by their rapid motion 

 through the air, which acts much more efficiently than the circu- 

 lation of water through the magnet-cylinder. By increasing the 

 diameter of the electromagnetic circles conjointly with the num- 

 ber of electromagnets and armatures, the angular velocity of the 



