( 216 ) 



N°. 95<^, XII. § 6. The resistance of the gold wire ran be represented 

 fairly well as far as — 217° as a function of the temperature by a 

 formula of the form A. 



—1=1+ 0,39070 h 0.017936 + 



Wo 100 ^ V looy ^ 



+ 0,0085684 (^—j + 0.0080999 (^— -^^^-j . (A) 



This formula A is not fit to include the hydrogen temperatures. 

 For the deviations W — Ra comp. table III. 



We have therefore made use of a formula B, and 

 t \ / « 



_i = 1 + 0,382404 (^-J + 0,0102335 (^^J + 



/^ t Y /lOO 100 \ 1 .„ .. 



+ 0,0035218(-J -0,0268911 (^^-^+ [ (B I) 



I /100\' / 100 \^ 



4- 0,0052211 U — „ ^^ 



I V T J V273,09y/ 



is in good harmony down to — 253°, while 



^;== 1 + 0,394548 (4) + 0,0200118(4)'+ 



/ t A» /lOO 100 \ 1 



+ 0,0102889 (-j + 0,0229106 (-^ " ^„-^ j \(B U) 



'loo^' / 100 



- 0,00094614 11 



T J V273,09 



)0 n 



gives a fair harmony also at — 259^ 



The deviations are given under the headings W—Rbi and W — Rbu 

 in columns 5 and 6 of table III. The mean error of an observation 

 with respect to the comparison with formula B I is ±0,017 52 in 

 resistance and ± 0°,09 in temperature. Formula B I gives for the 

 point of inflection of the gold resistance — 220°. 



Mathematics. — "■Quadratic complexes of revolution'' By Prof. 

 Jan de Vries. 



§ 1. When the rays of a complex can be arranged in reguli of 

 hyperboloids of revolution with the same axis, then the complex can 

 bear revolving about that axis. If such a complex of revolution i2 

 contains also the second regulus of each of the indicated hyperboloids, 

 then it is symmetric with respect to each plane through its axis 



1) The coefficients of the formulae and the values of the deviations, found at 

 a renewed calculation, differ slightly from those given in the original Dutch paper. 



