471 



the effect of a cooperation of (wo fields, one in the direction of ihe axis 

 of rotation and another |)arallel to the vertical plane throngh the 

 axis and perpendicular to the latter, which two fields bear a 

 proportion as for the strength as cos a : sin (t. Of those fields onlj 

 the latter can generate a current in W. 



When the changes in the electromotive force in IF in consequence 

 of changes in <r shall be proportional to shi a, the condition must 

 be made, that the magnetic field be unvariable when the relative 

 position of axis and lines of force changes. Therefore 1 the material 

 for the axis of rotation must be a non-magnetic one, and 2 if the 

 homogeneity is not to be relied upon, and if a weak iron core 

 shall be used, the form of the core must be globular. 



By combining the use of a dynamo axis driven by reaction by 

 an air screw with the slnusdynmno desci-ibed iiere in principle, a 

 system ia obtained by which currents are geneinted, proportional as 

 well to the total speed Vt of fig. 1, as to the sinus of the angle c. 

 under which the machine climbs or falls, (fig. 3) so that the strength 

 of those currents offers a diiect measure of the vertical velocity 

 with respect to the medium, which measure is independent of 

 the height of observation and of all quantities connected with the 

 machine, so that no correction whatever has to be applied. 



In fig. 4. the mechanism of such a sinusdynamo is illustrated 

 achematically. The armature has been executed in the most simple 

 way: the coil W has been imbedded in two parallel circular grooves 

 on both sides of the axis aa. In the magnet M the slits G allow 



the axis to take different positions with respect to the magiiet. The 

 axis pivots around 0, the point that at the same time determines 



