of view of the Kinetic Theory of Matt 



er 



27 



The radiometers in the present instance were designed to be 

 used at pressures corresponding to points lying on the sensibil- 

 ity curve between maximum and zero deflecting forces. The 













-=■ 

































100 













































/ 







































50 





/ 









































/ 









































60 













































■- 







































40 



/ 



















































































20 



















































































_ 

















































20 40 60 80 100 120 140 160 ISO 



Pressure in 10 — c atmospheres. 



cl¥ 



reason plainly being, that on this branch of the curve ^ has 



its maximum value, — F being deflecting force and P pressure. 

 On account of the somewhat uncertain, as well as intermit- 

 tent character of the potential-difference produced by an in- 

 duction coil actuated by a make and break in the primary cir- 

 cuit, it has been found most desirable and useful to employ an 

 alternating current, varying as a simple harmonic function of 

 the time, in the primary of the induction coil. The potential- 

 difference thus induced in the secondary circuit is alternating 



in character. By employing a two-part commutator, driven 

 by a synchronous motor, the alternating potential-diiference is 

 rectified as shown bv waves above the abscissas line in fig. 4. 



