Dr. C. Fromme on the Magnetism of Steel Bars. 195 



The close accordance between the values of a— b is not pecu- 

 liar to this example ; it appeared strikingly in almost all the 

 observations. At the same time, however, we see how enor- 

 mously small are the angles a and /3, even with so delicate a 

 galvanometer as was that made use of; at the commencement 

 it had an oscillation-period of nearly 37 seconds (later some- 

 what less). 



The difficulty of the observation is increased when ellipsoids 

 of less eccentricity (as Nos. 1 and 2) are employed. Under 

 the action of the horizontal component the difference of n and 

 n' amounted with No. 1 to not quite five, and with ISTo. 2 to 

 nine scale-divisions. 



During the four weeks which the observations occupied, the 

 temperature of the apartment only varied hetween 2*5 and 8 

 degrees Centigrade, a variation which, it is self-evident, did 

 not affect the observations. 



After two pairs of values of h and K were for the first time 

 found for each of the ellipsoids by means of the vertical compo- 

 nents, when the horizontal components had just begun to act 

 upon ellipsoids 1. 4 and I. 5 the inductor had to undergo repair. 

 When the injury (produced by the insulation being damaged) 

 was repaired, the observations were continued, each of the 

 ellipsoids being now subjected twice to the horizontal and then 

 once more to the vertical component. 



The values of G, k, and K are put together in Table II. ; 

 but the values obtained before the repair are distinguished 

 from the rest by prefixing an asterisk (*). 



§ 5. We will at present consider only the values of h 

 and K obtained after the inductor was repaired. The follow- 



Horizontal Component. 



ng are 



the means 



: — 



Vertical Com 



Donent. 





h. 



K. 



I. 1. 



15-9974 



0-2003 



2. 



11-8461 



0-3991 



3. 



10-4328 



0-5777 



4. 



9-8564 



0-8311 



5. 



8-6826 



1-3222 



II. 1. 



6-1380 



0-5039 



2. 



6-3318 



0-6890 



3. 



5-9333 



0-9601 



4. 



6-4917 



1-1539 



5. 



5-8772 



1-6867 



h. 



K. 



23-5034 



0-0610 



18-0285 



0-1062 



12-6030 



0-2121 



11-4105 



0-3189 



9-6467 



0-5311 



11-8347 



0-1199 



7-7361 



0-2511 



6-4746 



0-3879 



6-9191 



0-4762 



5-9691 



0-7228 



