Transpiration and Radiometer Motion. 





(vK)/2( 



02-Pl) 



B' 







A' 



Air 20 





•045 



• 



4 5 



H 2 18 



on 



•00917 





5 61 



h furnish the comparis 





f(k+ft)/2 ... 757 



594 



564 



288 



131 



88-9 



Air lp 2 ~Pi <»1- ••. '59 



•66 



•67 



•79 



•85 



•82 



L? ? 2-i , i ex p. ... '56 



•63 



•67 



•88 



•92 



•83 



f(P 2 +i>,)/2... 59-7 



31-7 



152 



6-35 



384 





Air-|# 2 — j^ca!. ... -77 



•64 



•45 



•24 



•17 





L^-^exp.... -74 



•58 



•38 



•20 



•17 





f(? 2 +l>i)/2 -. 858 



686 



508 



406 



339 



249 



H 2 J p 2 -pj_ oal. ... 3-56 

 l^ - Pi exp.... 340 



375 



3-91 



3-94 



392 



3-78 



3-65 



3-89 



3-89 



3-90 



3-82 



f(P a +l>i)/2 -. 203 



152 



82-5 



50-8 



17-8 



7-62 



H 2 1^2-^1 caL ••• 3 ' 62 



3-35 



2-55 



1-91 



•85 



•40 



{P-2-Pi ex P- ••• 3 "7 3 



335 



2'64 



1-93 



•84 



•40 



387 



These comparisons show that the equation (19) represents 

 the facts of thermal transpiration, for the discrepancies 

 between calculation and experiment are mostly of the same 

 order as the experimental uncertainty, as can be seen from a 

 careful comparison of the experimental data amongst them- 

 selves. 



We have now to consider the relation between the experi- 

 mental values of the parameters (t , 2 + vj) /2(v 2 — v x ) , B', and A.' 

 and their theoretical natures. First, as to (v 2 -r v 1 )/2(v 2 — v{), 

 which is equal to (0 2 * +0 1 *)/2(0 2 l — 6fy where 6 2 and 1 are 

 the temperatures of the two faces of the porous plate ; now 

 the walls between the jackets and the air-chambers are of 

 thin metal, and the chambers are of the same shape and size, 

 so that the mean of the temperatures 2 and 6 X must be 

 nearly equal to that of the two jacket temperatures i 2 and 

 i x ; thus 2 + 0i=4 + hj which, with the values given for 

 (v 2 ■ + i>i)/2 (v 2 — Vi) , suffices to determine 6 2 and d x . 



Meerschaum II. . 

 Meerschaum III. . 

 Stucco I. . . . 



i 



2 -273 

 (9 X — 273 



<9 2 -273 

 (9 1 -273 



2 — 273 

 tfj-273 



Air. 

 74 

 34 



H, 

 81 



27 



CO., 

 74 

 34 



77 79 



40-5 39 



76 77 



42-5 40 



