Eight miles above Hamburg the stream divides into the Norder (or Hamburg) Elbe and the Slider (or Harburg) Elbe, which are linked together by several cross-channels, and embrace in their arms the large island of Wilhelmsburg and some smaller ones.
- Slider of Kelvin Ampere Balance.
The slider is placed so as to touch the fine wire at division No.
If then we substitute for the standard cell any other source of electromotive force, we can move the slider into another position in which the galvanometer will show no deflection.
Instead of adjusting in this manner the electromotive force of any form of cell, if we pass any constant current through a known resistance and bring wires from the extremities of that resistance into connexion with the slider and the galvanometer terminal, we can in the same way determine the fall of potential down the above resistance in terms of the electromotive force of the standard cell and thus measure the current flowing through the standard resistance.
One terminal of the galvanometer can then be shifted to the junction 6 7 g between any pair of consecutive coils and the slider shifted to any point on the potentiometer wire.
We may employ such a potentiometer to measure large potential difference greater than the electromotive force of the working battery, as follows: The two points between which the potential difference is required are connected by high resistance, say of 100,000 ohms or more, and from the extremities of a known fraction of this resistance, say, 'Roo or I/1000 or I/Io,000 wires are brought to the potentiometer and connected in between the slider and the corresponding galvanometer terminal.
The slider upon the rule serves to adjust the scale for different temperatures, and then indicates the strength of the spirit in percentages over or under proof.
The slider is also provided with scales, marked respectively Dicas and Clarke, which serve to show the readings which would have been obtained had the instruments of those makers been employed.
The arm CD turns on the axis C, and -.~ .- is jointed at D to the middle of the bar ADB, whose length is double I of that of CD, and one of whose - ends B is jointed to a slider, sliding in straight guides along the line FIG 113.
A chain built up of three turning pairs and one sliding pair, and known as the slider crank chain, is shown in fig.
Foi example, there is a well-known mechanism corresponding to th fixing of three of the four links of the slider crank chain (fig.
Inversions of the slider crank chain.
Examples, completely worked out, of velocity and acceleration diagrams for the slider crank chain, the four-bar chain, and the mechanism of the Joy valve gear will be found in ch.
Now let PT be a tangent to the curve at P, cutting OX in T; PT=PYXsecant obliquity, and this is to be a constant quantity; hence the curve is that known as the tractory of the straight line OX, in which PT = OR = constant, This curve is described by having a fixed straight edge parallel to OX, along which slides a slider carrying a pin whose centre is T.