﻿1 



2 



\ 



f 



42-6 



89*2 



137-0 



43-8 



87-2 



137-0 



43-1 



88-8 



137-0 



238 Intelligence and Miscellaneous Articles. 



tensity of the current were within the errors of observation. If, for 

 instance, the mean be taken of the sets of observations on the 16th, 

 17th, and 18th of July, and those on the 25th and 26th of July, the 

 deflections, in parts of a scale, are — 



Velocity of rotation = § 



16th, 17th, and 18th of July =30*2 



25th and 26th of July =29' 7 



Mean =30*0 



The differences are similarly small if the mean be taken of other 

 groups. 



It is, secondly, remarkable that the electricity furnished is, within 

 the limits prescribed by the dimensions of the machine, as good as 

 independent of the distance between the combs and the rotating 

 plate, as follows from the following numbers, which also represent 

 the mean values of several experiments : — 



Velocity of rotation = i i -f f 



f 4 millims. 30-5 45'2 90*7 139*4 



Distance of the combs J 19 „ 30'0 460 89*2 131*7 



from the glass disk 1 27 „ 30"5 47'0 88*2 130'0 



[34 „ 30-9 46-0 87-1 130-3 



The working with a slow rotation remained unchanged ; with the 

 greatest velocity the diminution is only about 7 per cent. Hence for 

 a velocity of the particles of glass of 3 metres in a second, the dis- 

 charge and charge are as complete when the distance of the points is 

 34 millims. as it is when it is 4 millims. With a velocity of 6 to 9 

 metres the discharge would only be incomplete — a point which, like 

 any motion of electricity for which a measurable time is required, 

 would deserve further examination. (The above observations are 

 less trustworthy, owing to the greater variations which always ac- 

 companied the further removal of the combs. A few times a sudden 

 decrease in activity set in which extended to total cessation.) 



It is seen, thirdly, that there is an almost exact proportionality 

 between the intensity of the current and the velocity of rotation, for 

 which purpose it is sufficient to compare the numbers given above. 

 After introducing a small correction for magnitudes which are pro- 

 portional to the tangent of the angle of deflection, we have, in the 



Velocity of rotation 

 Deflection . . 



«™ 1 



1 



1 



3. 



% 6 



2 



1 



2 



= 30-0 



43-1 



88-7 



136-6 



while, assuming proportionality, we calculate 



Deflection... =29-9 44-8 89*7 134-5 



The productiveness of Holtz's machine was further compared with 

 that of a very good friction machine (made on Winter's plan by 

 Apel) which has a disk of 600 millims., and under favourable cir- 



