Intelligence and Miscellaneous Articles. 387 



With other metals the determination is difficult in consequence 

 of secondary processes. — Wiedemann's Beibldtter, 1880, No. 9, 

 pp. 681, 682. 



RESULTS OF PENDULUM EXPERIMENTS. 

 BY C. S. PEIRCE, ASSISTANT COAST AND GEODETIC SURVEY. 

 The following are the results obtained from observations made 

 by me, for the IJ.S. Coast and Geodetic Survey, at four important 

 stations, for the purpose of comparing the lengths of the seconds' 

 pendulum, together with reductions to the sea-level and to the 

 equator. In making the last reduction I have assumed the ellipti- 

 city to be = 1 : 293, which is the latest result from measurements 

 of arcs. ^t station. At sea-level. At equator, 



metre. metre. metre. 



Hoboken .... 0-9932052 0-9932074 0-9910003 



Paris 0-9939337 0-9939500 0-9910132 



Berlin 0-9942399 0-9942482 0-9909865 



Kew 0-9941776 0-9941790 0-9910083 



The differences of the figures in the last column from 0-991 

 metre, a value conveniently near their mean, when reduced to oscil- 

 lations per diem are: — Hoboken + -01 s ; Paris +0-58 8 ; Berlin 

 — 0'59 3 ; Kew -f-0-36 s . The following are the residuals of former 

 observations according to Clarke (' Geodesy,' p. 349) : — 



New York -f0-20 s ; Paris — 3-29 s ; Kew +2-89 s . 

 Colonel Clarke has used a value of the elliptieity = 1 : 292*2, de- 

 rived from pendulum experiments. This slight difference, how- 

 ever, is not important. 



It should be explained that the result for Hoboken is derived 

 from [T 2 Inv.] " Kegular Set," given on page 318, and also on 

 page 416 of the Eeport of the Superintendent of the U.S. Coast 

 and Geodetic Survey for 1876. This number is treated as explained 

 on page 319, where in the second line from the bottom for [T 2 Bev.] 

 read [T 2 Inv.]. The altitude of the Hoboken station is stated on 

 page 204. The numbers for the European stations are copied from 

 page 320. 



The length which I have taken as the metre has been derived 

 from the German Eichungsamt, as fully explained in my Report. 

 This is about 19-2 microns shorter than the quantity which is con- 

 sidered to be a metre in our own office of weights and measures, 

 and is admitted in Berlin to be doubtful. It is impossible to fix 

 the true metre at present ; but I have but little doubt the above 

 values will ultimately have to be diminished by about twenty mi- 

 crons on account of the error in the standard used. — Silliman's 

 American Journal, October 1880. 



ON THE ILLUMINATION OF ELECTRODES. 



BY R. COLLEY*. 



According to Slouguinoff (Journ. de la Soc. phys. chim. de St. 



Petersh.), the light is intermittent which appears at electrodes 



* Journal de Physique, 1880, ix. pp. 155-160. 



