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[Entered at ihe Posi-Offlee of New York, N.V., as Second-Class Matter.J 



A WEEKLY NEWSPAPER OF ALL THE ARTS AND SCIENCES. 



Eighth Year. 

 Vol. XV. No. 873. 



NEW YORK, March 28, 1890. 



Single Copies, Ten Cents. 

 §3.50 Per Year, in Advance. 



QUEEN'S NEW TRIPLE-PLATE TOEPLER-HOLTZ 

 MACHINE. 



On this page we print a cut showing some of the details of the 

 new Toepler-Holtz machine, which has just bei-n patented by 

 James W. Queen & Co., the well-known manufacturers of philo- 

 sophical apparatus and electrical test instruments. This machine, 

 unlike very many that have appeared from time to time, is not 

 simply a modification of the orthodox model, embodying certain 

 conveniences, but is an entirely new thing, owing its efficiency to 

 entirely novel ideas of construction and action. 



This machine, as its name indicates, is a three-plate machine ; 

 it is not, however, the same thing as the machine usually spoken 



effects, of possibly even greater importance than those just men- 

 tioned. The advantage of this new form of machine becomes 

 especially marked during moist weather. At such times ordinary 

 frictional machines will not work at all ; and all older text-books 

 direct that electrical experiments must be performed during Jan- 

 uary and February, when the weather is clear and dry. With the 

 Toepler-Holtz machine, as now known, this requirement has not 

 been so rigid, although such machines are not to be always trusted 

 during damp seasons, as lecturers have found out to their sorrow. 

 This difficulty it has been desired to do away with in this new 

 form, and that it does it very effectually will be evident from the 

 following letter sent to Queen & Co. by Professor William A. An- 

 thony, the well-known electrician, and late professor of physics at 



NEW TRIPLE-PLATE TOEPLER-HOLTZ MACHINE. 



of as the " double revolving plate machine," although it does have 

 two revolving plates. The latter machine is simply aa ordinary 

 Toepler-Holtz machine doubled ; i.e., with a revolving plate be- 

 hind the fixed plate, exactly like the one in front and acting in 

 exactly the same manner. In this new form, the additional plate 

 is not like the front revolving plate, nor does it act in at all the 

 same way. The third and additional plate is here a perfectly 

 plain glass plate, mounted upon the same axis as the usual revolv- 

 ing plate, and placed behind the fixed plate. Its modus operandi 

 is, like many other points in the theory of the Holtz machines, 

 not entirely understood, although there is no doubt but that much 

 of the increased efficiency obtained by its use is due to the screen- 

 ing effects it has upon the other plates ; i.e., to the leakage that 

 is prevented by its presence. There is also supposed to be a con- 

 siderable generation of electricity by friction of the plain plate and 

 the ail'. Undoubtedly many other causes also tend to increased 



Cornell University. Says he, "Below is a report of the small 

 Holtz machines you sent up a few days ago. First, in order to 

 determine whether the extra plate gave any increased effect to 

 the machine, I set up both machines, and arranged (liem so that 

 they both could be revolved by means of one crank, and so that 

 they would both run at the same speed, and then adjusted the 

 termiuals until the sparks occurred with about the same fre- 

 quency in both. Then I removed the combs from one of them, 

 so that the third plate would have no effect in the development of 

 electricity, and found that the frequency of sparks on that machine 

 was very much less than on the other. I repeated this several 

 times, with the same result, and tried the same experiment on 

 the other machine ; that is, leaving the combs on the first ma- 

 chine, I removed them from the second, when that one was found 

 to give considerably less electricity than the first. I can say un- 

 hesitatingly, therefore, that the addition of the thud plate does 



