114 



M. E. Pringsheim on the Radiometer. 



With bright Gas-flame. 



With dull Gas-flame. 





L. 



A. 



L. 



A. 



L. 



A. 





L. 



A. 



L. 



A. 



I. 



II. 

 III. 

 IV. 



V. 



500 

 585 

 462 

 376 

 500 



85 

 38 

 86 



500 

 587 

 462 

 376 

 500 



87 

 38 

 86 



500 

 642 

 485 

 344 

 500 



142 



15 



141 



I. 



II. 

 III. 

 IV. 



V. 



500 

 549 

 441 

 390 

 500 



49 

 59 

 51 



500 

 549 

 445 

 397 

 500 



49 

 55 



48 



Here the numbers in the columns superscribed with L. 

 denote, in the horizontal rows: — 



I. The resting-position of the index when the apparatus is 

 shaded with a screen. 



II. The extreme deflection of the index at the moment of 

 the removal of the screen. 



III. The resting-position of the index on full irradiation. 



IV. The extreme deflection at the moment of shading. 

 V. The resting-position during the shading. 



The numbers in the columns A. give the deflections from 

 the next preceding resting-position, which correspond to the 

 numbers standing on the left side of them. 



As these deflections are not very great, and are pretty much 

 of the same order as the previous ones produced by the absorp- 

 tion of the glass, it suggested itself that this absorption might 

 exert a disturbing influence which would be likely to mask 

 the proper motion produced by the vanes. On this account, 

 in a second series of experiments the light, before arriving at 

 the apparatus, was cleared of its most absorbable rays by three 

 thick glass plates. The following results were then obtained 

 (the notation having the same meaning as before) : — 



Bright Gas-flame. 



Dull Gas-flame. 





L. 



A. 



L. 



A. 



L. 



A. 





L. 



A. 



I. 



II. 

 III. 

 IV. 



V. 



500 

 587 

 477 

 386 

 500 



87 

 23 

 91 



500 

 585 

 482 

 394 

 500 



85 

 18 

 88 



500 



584 

 483 

 398 

 500 



84 

 17 



85 



I. 



II. 

 III. 

 IV. 



V. 



500 

 519 

 479 

 459 

 500 



19 

 21 



20 



